diff --git a/src/libexpr/diagnostic.hh b/src/libexpr/diagnostic.hh
new file mode 100644
index 00000000000..d164dec0ac6
--- /dev/null
+++ b/src/libexpr/diagnostic.hh
@@ -0,0 +1,223 @@
+/**
+ * diagnostic.hh - This file declares records that related to nix diagnostic
+ *
+ * Diagnostics are structures with a main message,
+ * and optionally some additional information (body).
+ *
+ * For diagnostics with a body,
+ * they may need a special overrided function to format the message.
+ *
+ */
+#pragma once
+
+#include <string>
+#include <vector>
+
+#include "error.hh"
+#include "nixexpr.hh"
+
+namespace nix {
+
+/**
+ * The base class for all diagnostics.
+ * concret diagnostic types are defined in Diagnostic*.inc
+ */
+struct Diag
+{
+ /**
+ * The location of some diagnostic, currently it is at the beginning of tokens
+ */
+ PosIdx loc;
+
+ /**
+ * Unique identifier for internal use.
+ */
+ enum Kind {
+#define DIAG_MERGE(SNAME, CNAME, SEVERITY) DK_##CNAME,
+#include "diagnostics/merge.inc"
+ };
+
+ Diag() = default;
+ Diag(PosIdx loc)
+ : loc(loc){};
+
+ /**
+ * Each diagnostic contains a severity field,
+ * should be "Fatal", "Error" or "Warning"
+ * this will affect the eval process.
+ *
+ * "Fatal" -- non-recoverable while parsing.
+ * "Error" -- recoverable while parsing, but should not eval
+ * "Warning" -- recoverable while parsing, and we can eval the AST
+ * "Note" -- some additional information about the error.
+ */
+ enum Severity { DS_Fatal, DS_Error, DS_Warning, DS_Note };
+
+ [[nodiscard]] virtual Kind kind() const = 0;
+
+ /**
+ * \brief short name.
+ * There might be a human readable short name that controls the diagnostic
+ * For example, one may pass -Wno-dup-formal to suppress duplicated formals.
+ * A special case for parsing errors, generated from bison
+ * have the sname "bison"
+ */
+ [[nodiscard]] virtual std::string_view sname() const = 0;
+
+ /** Get severity */
+ [[nodiscard]] virtual Severity severity() const = 0;
+
+ /**
+ * Format printable diagnostic, with string interpolated
+ * e.g. "invalid integer %1%" -> "invalid integer 'bar'"
+ */
+ [[nodiscard]] virtual std::string_view format() const = 0;
+
+ virtual ~Diag() = default;
+
+ static Verbosity getVerb(Severity s)
+ {
+ switch (s) {
+ case DS_Error:
+ case DS_Fatal:
+ return lvlError;
+ case DS_Warning:
+ return lvlWarn;
+ case DS_Note:
+ return lvlNotice;
+ }
+ }
+
+ [[nodiscard]] ErrorInfo getErrorInfo(const PosTable & positions) const
+ {
+ return ErrorInfo{.msg = std::string(format()), .errPos = positions[loc]};
+ }
+
+ using Notes = std::vector<std::shared_ptr<Diag>>;
+
+ [[nodiscard]] virtual Notes getNotes() const
+ {
+ return {};
+ }
+};
+
+struct DiagWithNotes : Diag
+{
+ Diag::Notes notes;
+ [[nodiscard]] Diag::Notes getNotes() const override
+ {
+ return notes;
+ }
+};
+
+#define DIAG_SIMPLE(SNAME, CNAME, SEVERITY, MESSAGE) \
+ struct Diag##CNAME : Diag \
+ { \
+ std::string_view format() const override \
+ { \
+ return MESSAGE; \
+ } \
+ std::string_view sname() const override \
+ { \
+ return SNAME; \
+ } \
+ Severity severity() const override \
+ { \
+ return DS_##SEVERITY; \
+ } \
+ Kind kind() const override \
+ { \
+ return DK_##CNAME; \
+ } \
+ Diag##CNAME() = default; \
+ Diag##CNAME(PosIdx pos) \
+ : Diag(pos) \
+ { \
+ } \
+ };
+#include "diagnostics/kinds.inc"
+#undef DIAG_SIMPLE
+
+#define DIAG_BODY(SNAME, CNAME, SEVERITY, BODY) struct Diag##CNAME : Diag BODY;
+#include "diagnostics/kinds.inc"
+#undef DIAG_BODY
+
+// Implement trivial functions except ::format
+#define DIAG_BODY(SNAME, CNAME, SEVERITY, BODY) \
+ inline std::string_view Diag##CNAME::sname() const \
+ { \
+ return SNAME; \
+ } \
+ inline Diag::Severity Diag##CNAME::severity() const \
+ { \
+ return DS_##SEVERITY; \
+ } \
+ inline Diag::Kind Diag##CNAME::kind() const \
+ { \
+ return DK_##CNAME; \
+ }
+#include "diagnostics/kinds.inc"
+#undef DIAG_BODY
+
+inline DiagInvalidInteger::DiagInvalidInteger(PosIdx loc, std::string text)
+ : Diag(loc)
+ , text(std::move(text))
+{
+ text = hintfmt("invalid integer '%1%'", text).str();
+}
+
+inline DiagInvalidFloat::DiagInvalidFloat(PosIdx loc, std::string text)
+ : Diag(loc)
+ , text(std::move(text))
+{
+ text = hintfmt("invalid float '%1%'", text).str();
+}
+
+inline std::string_view DiagInvalidInteger::format() const
+{
+ return text;
+}
+
+inline std::string_view DiagInvalidFloat::format() const
+{
+ return text;
+}
+
+inline std::string_view DiagBisonParse::format() const
+{
+ return err;
+}
+struct DiagnosticEngine
+{
+ std::vector<std::unique_ptr<Diag>> errors;
+ std::vector<std::unique_ptr<Diag>> warnings;
+
+ void add(std::unique_ptr<Diag> D)
+ {
+ switch (D->severity()) {
+ case Diag::DS_Fatal:
+ case Diag::DS_Error: {
+ errors.emplace_back(std::move(D));
+ break;
+ }
+ case Diag::DS_Warning: {
+ warnings.emplace_back(std::move(D));
+ break;
+ }
+ case Diag::DS_Note: {
+ // todo: unreachble
+ assert(0);
+ }
+ }
+ }
+
+ void checkRaise(const PosTable & positions) const
+ {
+ if (!errors.empty()) {
+ const Diag * back = errors[0].get();
+ throw ParseError(back->getErrorInfo(positions));
+ }
+ }
+};
+
+} // namespace nix
diff --git a/src/libexpr/diagnostics/kinds.inc b/src/libexpr/diagnostics/kinds.inc
new file mode 100644
index 00000000000..c6e13fc8851
--- /dev/null
+++ b/src/libexpr/diagnostics/kinds.inc
@@ -0,0 +1,49 @@
+/// diagnostics/kinds.inc, provides declarations for diagnostics.
+
+// provides: DIAG_SIMPLE(SNAME, CNAME, SEVERITY, MESSAGE)
+// provides: DIAG_BODY(SNAME, CNAME, SEVERITY, BODY)
+// provides: DIAG_NOTE_SIMPLE(SNAME, CNAME, SEVERITY, MESSAGE)
+// provides: DIAG_NOTE_BODY(SNAME, CNAME, SEVERITY, BODY)
+
+//=============================================================================/
+// DIAG_SIMPLE(SName, ClassName, Severity, Message)
+// "simple" means they have no additional body
+//=============================================================================/
+
+#ifdef DIAG_SIMPLE
+DIAG_SIMPLE("path-trailing-slash", PathTrailingSlash, Error, "path has a trailing slash")
+DIAG_SIMPLE("dynamic-in-let", DynamicInLet, Error, "dynamic attributes not allowed in let")
+DIAG_SIMPLE("dynamic-in-inherit", InheritDynamic, Error, "dynamic attributes not allowed in inherit")
+DIAG_SIMPLE("url-literal", URLLiteral, Warning, "url literals are disabled")
+DIAG_SIMPLE("hpath-impure", HPath, Error, "hpath cannot be resolved in pure mode")
+#endif
+
+#define COMMON_BODY \
+ Severity severity() const override; \
+ Kind kind() const override; \
+ std::string_view format() const override; \
+ std::string_view sname() const override;
+
+//=============================================================================/
+// DIAG_BODY(SName, ClassName, Severity, Body)
+// diagnostics with special body
+//=============================================================================/
+#ifdef DIAG_BODY
+DIAG_BODY("bison", BisonParse, Fatal, {
+ std::string err;
+ COMMON_BODY
+})
+DIAG_BODY("invalid-integer", InvalidInteger, Fatal, {
+ std::string text;
+ COMMON_BODY
+ DiagInvalidInteger(PosIdx loc, std::string text);
+})
+
+DIAG_BODY("invalid-float", InvalidFloat, Fatal, {
+ std::string text;
+ COMMON_BODY
+ DiagInvalidFloat(PosIdx loc, std::string text);
+})
+
+#undef COMMON_BODY
+#endif // DIAG_BODY
diff --git a/src/libexpr/diagnostics/merge.inc b/src/libexpr/diagnostics/merge.inc
new file mode 100644
index 00000000000..3861491bd41
--- /dev/null
+++ b/src/libexpr/diagnostics/merge.inc
@@ -0,0 +1,17 @@
+// diagnostics/merge.inc, merge all declarations
+
+// provides: DIAG_MERGE(SNAME, CNAME, SEVERITY)
+
+#ifdef DIAG_MERGE
+
+#define DIAG_SIMPLE(SNAME, CNAME, SEVERITY, MESSAGE) DIAG_MERGE(SNAME, CNAME, SEVERITY)
+#define DIAG_BODY(SNAME, CNAME, SEVERITY, BODY) DIAG_MERGE(SNAME, CNAME, SEVERITY)
+#define DIAG_NOTE_SIMPLE(SNAME, CNAME, SEVERITY, MESSAGE) DIAG_MERGE(SNAME, CNAME, SEVERITY)
+
+#include "kinds.inc"
+
+#undef DIAG_NOTE_SIMPLE
+#undef DIAG_BODY
+#undef DIAG_SIMPLE
+
+#endif
diff --git a/src/libexpr/lexer.l b/src/libexpr/lexer/lexer.l
similarity index 68%
rename from src/libexpr/lexer.l
rename to src/libexpr/lexer/lexer.l
index a3a8608d9a7..d35fb1000f1 100644
--- a/src/libexpr/lexer.l
+++ b/src/libexpr/lexer/lexer.l
@@ -15,98 +15,7 @@
%{
-#ifdef __clang__
-#pragma clang diagnostic ignored "-Wunneeded-internal-declaration"
-#endif
-
-#include <boost/lexical_cast.hpp>
-
-#include "nixexpr.hh"
-#include "parser-tab.hh"
-
-using namespace nix;
-
-namespace nix {
-
-static inline PosIdx makeCurPos(const YYLTYPE & loc, ParseData * data)
-{
- return data->state.positions.add(data->origin, loc.first_line, loc.first_column);
-}
-
-#define CUR_POS makeCurPos(*yylloc, data)
-
-// backup to recover from yyless(0)
-thread_local YYLTYPE prev_yylloc;
-
-static void initLoc(YYLTYPE * loc)
-{
- loc->first_line = loc->last_line = 1;
- loc->first_column = loc->last_column = 1;
-}
-
-static void adjustLoc(YYLTYPE * loc, const char * s, size_t len)
-{
- prev_yylloc = *loc;
-
- loc->first_line = loc->last_line;
- loc->first_column = loc->last_column;
-
- for (size_t i = 0; i < len; i++) {
- switch (*s++) {
- case '\r':
- if (*s == '\n') { /* cr/lf */
- i++;
- s++;
- }
- /* fall through */
- case '\n':
- ++loc->last_line;
- loc->last_column = 1;
- break;
- default:
- ++loc->last_column;
- }
- }
-}
-
-
-// we make use of the fact that the parser receives a private copy of the input
-// string and can munge around in it.
-static StringToken unescapeStr(SymbolTable & symbols, char * s, size_t length)
-{
- char * result = s;
- char * t = s;
- char c;
- // the input string is terminated with *two* NULs, so we can safely take
- // *one* character after the one being checked against.
- while ((c = *s++)) {
- if (c == '\\') {
- c = *s++;
- if (c == 'n') *t = '\n';
- else if (c == 'r') *t = '\r';
- else if (c == 't') *t = '\t';
- else *t = c;
- }
- else if (c == '\r') {
- /* Normalise CR and CR/LF into LF. */
- *t = '\n';
- if (*s == '\n') s++; /* cr/lf */
- }
- else *t = c;
- t++;
- }
- return {result, size_t(t - result)};
-}
-
-
-}
-
-#define YY_USER_INIT initLoc(yylloc)
-#define YY_USER_ACTION adjustLoc(yylloc, yytext, yyleng);
-
-#define PUSH_STATE(state) yy_push_state(state, yyscanner)
-#define POP_STATE() yy_pop_state(yyscanner)
-
+#include "lexer/prologue.inc"
%}
@@ -153,20 +62,17 @@ or { return OR_KW; }
try {
yylval->n = boost::lexical_cast<int64_t>(yytext);
} catch (const boost::bad_lexical_cast &) {
- throw ParseError({
- .msg = hintfmt("invalid integer '%1%'", yytext),
- .errPos = data->state.positions[CUR_POS],
- });
+ data->diags.add(std::make_unique<DiagInvalidInteger>(CUR_POS, yytext));
+ yyterminate();
}
return INT;
}
{FLOAT} { errno = 0;
yylval->nf = strtod(yytext, 0);
- if (errno != 0)
- throw ParseError({
- .msg = hintfmt("invalid float '%1%'", yytext),
- .errPos = data->state.positions[CUR_POS],
- });
+ if (errno != 0) {
+ data->diags.add(std::make_unique<DiagInvalidFloat>(CUR_POS, yytext));
+ yyterminate();
+ }
return FLOAT;
}
@@ -292,10 +198,8 @@ or { return OR_KW; }
<INPATH_SLASH>{ANY} |
<INPATH_SLASH><<EOF>> {
- throw ParseError({
- .msg = hintfmt("path has a trailing slash"),
- .errPos = data->state.positions[CUR_POS],
- });
+ data->diags.add(std::make_unique<DiagPathTrailingSlash>(CUR_POS));
+ yyterminate();
}
{SPATH} { yylval->path = {yytext, (size_t) yyleng}; return SPATH; }
diff --git a/src/libexpr/lexer/prologue.inc b/src/libexpr/lexer/prologue.inc
new file mode 100644
index 00000000000..2a966af04f1
--- /dev/null
+++ b/src/libexpr/lexer/prologue.inc
@@ -0,0 +1,93 @@
+#ifdef __clang__
+#pragma clang diagnostic ignored "-Wunneeded-internal-declaration"
+#endif
+
+#include <boost/lexical_cast.hpp>
+
+#include "nixexpr.hh"
+#include "parser-tab.hh"
+
+using namespace nix;
+
+namespace nix {
+
+static inline PosIdx makeCurPos(const YYLTYPE & loc, ParseData * data)
+{
+ return data->state.positions.add(data->origin, loc.first_line, loc.first_column);
+}
+
+#define CUR_POS makeCurPos(*yylloc, data)
+
+// backup to recover from yyless(0)
+thread_local YYLTYPE prev_yylloc;
+
+static void initLoc(YYLTYPE * loc)
+{
+ loc->first_line = loc->last_line = 1;
+ loc->first_column = loc->last_column = 1;
+}
+
+static void adjustLoc(YYLTYPE * loc, const char * s, size_t len)
+{
+ prev_yylloc = *loc;
+
+ loc->first_line = loc->last_line;
+ loc->first_column = loc->last_column;
+
+ for (size_t i = 0; i < len; i++) {
+ switch (*s++) {
+ case '\r':
+ if (*s == '\n') { /* cr/lf */
+ i++;
+ s++;
+ }
+ /* fall through */
+ case '\n':
+ ++loc->last_line;
+ loc->last_column = 1;
+ break;
+ default:
+ ++loc->last_column;
+ }
+ }
+}
+
+// we make use of the fact that the parser receives a private copy of the input
+// string and can munge around in it.
+static StringToken unescapeStr(SymbolTable & symbols, char * s, size_t length)
+{
+ char * result = s;
+ char * t = s;
+ char c;
+ // the input string is terminated with *two* NULs, so we can safely take
+ // *one* character after the one being checked against.
+ while ((c = *s++)) {
+ if (c == '\\') {
+ c = *s++;
+ if (c == 'n')
+ *t = '\n';
+ else if (c == 'r')
+ *t = '\r';
+ else if (c == 't')
+ *t = '\t';
+ else
+ *t = c;
+ } else if (c == '\r') {
+ /* Normalise CR and CR/LF into LF. */
+ *t = '\n';
+ if (*s == '\n')
+ s++; /* cr/lf */
+ } else
+ *t = c;
+ t++;
+ }
+ return {result, size_t(t - result)};
+}
+
+} // namespace nix
+
+#define YY_USER_INIT initLoc(yylloc)
+#define YY_USER_ACTION adjustLoc(yylloc, yytext, yyleng);
+
+#define PUSH_STATE(state) yy_push_state(state, yyscanner)
+#define POP_STATE() yy_pop_state(yyscanner)
diff --git a/src/libexpr/local.mk b/src/libexpr/local.mk
index d243b9cec1d..b09828921cb 100644
--- a/src/libexpr/local.mk
+++ b/src/libexpr/local.mk
@@ -28,10 +28,10 @@ libexpr_LDFLAGS_PROPAGATED = $(BDW_GC_LIBS)
libexpr_ORDER_AFTER := $(d)/parser-tab.cc $(d)/parser-tab.hh $(d)/lexer-tab.cc $(d)/lexer-tab.hh
-$(d)/parser-tab.cc $(d)/parser-tab.hh: $(d)/parser.y
+$(d)/parser-tab.cc $(d)/parser-tab.hh: $(d)/parser/parser.y $(d)/parser/prologue.inc $(d)/parser/epilogue.inc
$(trace-gen) bison -v -o $(libexpr_DIR)/parser-tab.cc $< -d
-$(d)/lexer-tab.cc $(d)/lexer-tab.hh: $(d)/lexer.l
+$(d)/lexer-tab.cc $(d)/lexer-tab.hh: $(d)/lexer/lexer.l $(d)/lexer/prologue.inc
$(trace-gen) flex --outfile $(libexpr_DIR)/lexer-tab.cc --header-file=$(libexpr_DIR)/lexer-tab.hh $<
clean-files += $(d)/parser-tab.cc $(d)/parser-tab.hh $(d)/lexer-tab.cc $(d)/lexer-tab.hh
diff --git a/src/libexpr/parser.y b/src/libexpr/parser.y
deleted file mode 100644
index 70228e1e273..00000000000
--- a/src/libexpr/parser.y
+++ /dev/null
@@ -1,826 +0,0 @@
-%glr-parser
-%define api.pure
-%locations
-%define parse.error verbose
-%defines
-/* %no-lines */
-%parse-param { void * scanner }
-%parse-param { nix::ParseData * data }
-%lex-param { void * scanner }
-%lex-param { nix::ParseData * data }
-%expect 1
-%expect-rr 1
-
-%code requires {
-
-#ifndef BISON_HEADER
-#define BISON_HEADER
-
-#include <variant>
-
-#include "util.hh"
-
-#include "nixexpr.hh"
-#include "eval.hh"
-#include "eval-settings.hh"
-#include "globals.hh"
-
-namespace nix {
-
- struct ParseData
- {
- EvalState & state;
- SymbolTable & symbols;
- Expr * result;
- SourcePath basePath;
- PosTable::Origin origin;
- std::optional<ErrorInfo> error;
- };
-
- struct ParserFormals {
- std::vector<Formal> formals;
- bool ellipsis = false;
- };
-
-}
-
-// using C a struct allows us to avoid having to define the special
-// members that using string_view here would implicitly delete.
-struct StringToken {
- const char * p;
- size_t l;
- bool hasIndentation;
- operator std::string_view() const { return {p, l}; }
-};
-
-#define YY_DECL int yylex \
- (YYSTYPE * yylval_param, YYLTYPE * yylloc_param, yyscan_t yyscanner, nix::ParseData * data)
-
-#endif
-
-}
-
-%{
-
-#include "parser-tab.hh"
-#include "lexer-tab.hh"
-
-YY_DECL;
-
-using namespace nix;
-
-
-namespace nix {
-
-
-static void dupAttr(const EvalState & state, const AttrPath & attrPath, const PosIdx pos, const PosIdx prevPos)
-{
- throw ParseError({
- .msg = hintfmt("attribute '%1%' already defined at %2%",
- showAttrPath(state.symbols, attrPath), state.positions[prevPos]),
- .errPos = state.positions[pos]
- });
-}
-
-static void dupAttr(const EvalState & state, Symbol attr, const PosIdx pos, const PosIdx prevPos)
-{
- throw ParseError({
- .msg = hintfmt("attribute '%1%' already defined at %2%", state.symbols[attr], state.positions[prevPos]),
- .errPos = state.positions[pos]
- });
-}
-
-
-static void addAttr(ExprAttrs * attrs, AttrPath && attrPath,
- Expr * e, const PosIdx pos, const nix::EvalState & state)
-{
- AttrPath::iterator i;
- // All attrpaths have at least one attr
- assert(!attrPath.empty());
- // Checking attrPath validity.
- // ===========================
- for (i = attrPath.begin(); i + 1 < attrPath.end(); i++) {
- if (i->symbol) {
- ExprAttrs::AttrDefs::iterator j = attrs->attrs.find(i->symbol);
- if (j != attrs->attrs.end()) {
- if (!j->second.inherited) {
- ExprAttrs * attrs2 = dynamic_cast<ExprAttrs *>(j->second.e);
- if (!attrs2) dupAttr(state, attrPath, pos, j->second.pos);
- attrs = attrs2;
- } else
- dupAttr(state, attrPath, pos, j->second.pos);
- } else {
- ExprAttrs * nested = new ExprAttrs;
- attrs->attrs[i->symbol] = ExprAttrs::AttrDef(nested, pos);
- attrs = nested;
- }
- } else {
- ExprAttrs *nested = new ExprAttrs;
- attrs->dynamicAttrs.push_back(ExprAttrs::DynamicAttrDef(i->expr, nested, pos));
- attrs = nested;
- }
- }
- // Expr insertion.
- // ==========================
- if (i->symbol) {
- ExprAttrs::AttrDefs::iterator j = attrs->attrs.find(i->symbol);
- if (j != attrs->attrs.end()) {
- // This attr path is already defined. However, if both
- // e and the expr pointed by the attr path are two attribute sets,
- // we want to merge them.
- // Otherwise, throw an error.
- auto ae = dynamic_cast<ExprAttrs *>(e);
- auto jAttrs = dynamic_cast<ExprAttrs *>(j->second.e);
- if (jAttrs && ae) {
- for (auto & ad : ae->attrs) {
- auto j2 = jAttrs->attrs.find(ad.first);
- if (j2 != jAttrs->attrs.end()) // Attr already defined in iAttrs, error.
- dupAttr(state, ad.first, j2->second.pos, ad.second.pos);
- jAttrs->attrs.emplace(ad.first, ad.second);
- }
- jAttrs->dynamicAttrs.insert(jAttrs->dynamicAttrs.end(), ae->dynamicAttrs.begin(), ae->dynamicAttrs.end());
- } else {
- dupAttr(state, attrPath, pos, j->second.pos);
- }
- } else {
- // This attr path is not defined. Let's create it.
- attrs->attrs.emplace(i->symbol, ExprAttrs::AttrDef(e, pos));
- e->setName(i->symbol);
- }
- } else {
- attrs->dynamicAttrs.push_back(ExprAttrs::DynamicAttrDef(i->expr, e, pos));
- }
-}
-
-
-static Formals * toFormals(ParseData & data, ParserFormals * formals,
- PosIdx pos = noPos, Symbol arg = {})
-{
- std::sort(formals->formals.begin(), formals->formals.end(),
- [] (const auto & a, const auto & b) {
- return std::tie(a.name, a.pos) < std::tie(b.name, b.pos);
- });
-
- std::optional<std::pair<Symbol, PosIdx>> duplicate;
- for (size_t i = 0; i + 1 < formals->formals.size(); i++) {
- if (formals->formals[i].name != formals->formals[i + 1].name)
- continue;
- std::pair thisDup{formals->formals[i].name, formals->formals[i + 1].pos};
- duplicate = std::min(thisDup, duplicate.value_or(thisDup));
- }
- if (duplicate)
- throw ParseError({
- .msg = hintfmt("duplicate formal function argument '%1%'", data.symbols[duplicate->first]),
- .errPos = data.state.positions[duplicate->second]
- });
-
- Formals result;
- result.ellipsis = formals->ellipsis;
- result.formals = std::move(formals->formals);
-
- if (arg && result.has(arg))
- throw ParseError({
- .msg = hintfmt("duplicate formal function argument '%1%'", data.symbols[arg]),
- .errPos = data.state.positions[pos]
- });
-
- delete formals;
- return new Formals(std::move(result));
-}
-
-
-static Expr * stripIndentation(const PosIdx pos, SymbolTable & symbols,
- std::vector<std::pair<PosIdx, std::variant<Expr *, StringToken>>> && es)
-{
- if (es.empty()) return new ExprString("");
-
- /* Figure out the minimum indentation. Note that by design
- whitespace-only final lines are not taken into account. (So
- the " " in "\n ''" is ignored, but the " " in "\n foo''" is.) */
- bool atStartOfLine = true; /* = seen only whitespace in the current line */
- size_t minIndent = 1000000;
- size_t curIndent = 0;
- for (auto & [i_pos, i] : es) {
- auto * str = std::get_if<StringToken>(&i);
- if (!str || !str->hasIndentation) {
- /* Anti-quotations and escaped characters end the current start-of-line whitespace. */
- if (atStartOfLine) {
- atStartOfLine = false;
- if (curIndent < minIndent) minIndent = curIndent;
- }
- continue;
- }
- for (size_t j = 0; j < str->l; ++j) {
- if (atStartOfLine) {
- if (str->p[j] == ' ')
- curIndent++;
- else if (str->p[j] == '\n') {
- /* Empty line, doesn't influence minimum
- indentation. */
- curIndent = 0;
- } else {
- atStartOfLine = false;
- if (curIndent < minIndent) minIndent = curIndent;
- }
- } else if (str->p[j] == '\n') {
- atStartOfLine = true;
- curIndent = 0;
- }
- }
- }
-
- /* Strip spaces from each line. */
- auto * es2 = new std::vector<std::pair<PosIdx, Expr *>>;
- atStartOfLine = true;
- size_t curDropped = 0;
- size_t n = es.size();
- auto i = es.begin();
- const auto trimExpr = [&] (Expr * e) {
- atStartOfLine = false;
- curDropped = 0;
- es2->emplace_back(i->first, e);
- };
- const auto trimString = [&] (const StringToken & t) {
- std::string s2;
- for (size_t j = 0; j < t.l; ++j) {
- if (atStartOfLine) {
- if (t.p[j] == ' ') {
- if (curDropped++ >= minIndent)
- s2 += t.p[j];
- }
- else if (t.p[j] == '\n') {
- curDropped = 0;
- s2 += t.p[j];
- } else {
- atStartOfLine = false;
- curDropped = 0;
- s2 += t.p[j];
- }
- } else {
- s2 += t.p[j];
- if (t.p[j] == '\n') atStartOfLine = true;
- }
- }
-
- /* Remove the last line if it is empty and consists only of
- spaces. */
- if (n == 1) {
- std::string::size_type p = s2.find_last_of('\n');
- if (p != std::string::npos && s2.find_first_not_of(' ', p + 1) == std::string::npos)
- s2 = std::string(s2, 0, p + 1);
- }
-
- es2->emplace_back(i->first, new ExprString(std::move(s2)));
- };
- for (; i != es.end(); ++i, --n) {
- std::visit(overloaded { trimExpr, trimString }, i->second);
- }
-
- /* If this is a single string, then don't do a concatenation. */
- if (es2->size() == 1 && dynamic_cast<ExprString *>((*es2)[0].second)) {
- auto *const result = (*es2)[0].second;
- delete es2;
- return result;
- }
- return new ExprConcatStrings(pos, true, es2);
-}
-
-
-static inline PosIdx makeCurPos(const YYLTYPE & loc, ParseData * data)
-{
- return data->state.positions.add(data->origin, loc.first_line, loc.first_column);
-}
-
-#define CUR_POS makeCurPos(*yylocp, data)
-
-
-}
-
-
-void yyerror(YYLTYPE * loc, yyscan_t scanner, ParseData * data, const char * error)
-{
- data->error = {
- .msg = hintfmt(error),
- .errPos = data->state.positions[makeCurPos(*loc, data)]
- };
-}
-
-
-%}
-
-%union {
- // !!! We're probably leaking stuff here.
- nix::Expr * e;
- nix::ExprList * list;
- nix::ExprAttrs * attrs;
- nix::ParserFormals * formals;
- nix::Formal * formal;
- nix::NixInt n;
- nix::NixFloat nf;
- StringToken id; // !!! -> Symbol
- StringToken path;
- StringToken uri;
- StringToken str;
- std::vector<nix::AttrName> * attrNames;
- std::vector<std::pair<nix::PosIdx, nix::Expr *>> * string_parts;
- std::vector<std::pair<nix::PosIdx, std::variant<nix::Expr *, StringToken>>> * ind_string_parts;
-}
-
-%type <e> start expr expr_function expr_if expr_op
-%type <e> expr_select expr_simple expr_app
-%type <list> expr_list
-%type <attrs> binds
-%type <formals> formals
-%type <formal> formal
-%type <attrNames> attrs attrpath
-%type <string_parts> string_parts_interpolated
-%type <ind_string_parts> ind_string_parts
-%type <e> path_start string_parts string_attr
-%type <id> attr
-%token <id> ID
-%token <str> STR IND_STR
-%token <n> INT
-%token <nf> FLOAT
-%token <path> PATH HPATH SPATH PATH_END
-%token <uri> URI
-%token IF THEN ELSE ASSERT WITH LET IN REC INHERIT EQ NEQ AND OR IMPL OR_KW
-%token DOLLAR_CURLY /* == ${ */
-%token IND_STRING_OPEN IND_STRING_CLOSE
-%token ELLIPSIS
-
-%right IMPL
-%left OR
-%left AND
-%nonassoc EQ NEQ
-%nonassoc '<' '>' LEQ GEQ
-%right UPDATE
-%left NOT
-%left '+' '-'
-%left '*' '/'
-%right CONCAT
-%nonassoc '?'
-%nonassoc NEGATE
-
-%%
-
-start: expr { data->result = $1; };
-
-expr: expr_function;
-
-expr_function
- : ID ':' expr_function
- { $$ = new ExprLambda(CUR_POS, data->symbols.create($1), 0, $3); }
- | '{' formals '}' ':' expr_function
- { $$ = new ExprLambda(CUR_POS, toFormals(*data, $2), $5); }
- | '{' formals '}' '@' ID ':' expr_function
- {
- auto arg = data->symbols.create($5);
- $$ = new ExprLambda(CUR_POS, arg, toFormals(*data, $2, CUR_POS, arg), $7);
- }
- | ID '@' '{' formals '}' ':' expr_function
- {
- auto arg = data->symbols.create($1);
- $$ = new ExprLambda(CUR_POS, arg, toFormals(*data, $4, CUR_POS, arg), $7);
- }
- | ASSERT expr ';' expr_function
- { $$ = new ExprAssert(CUR_POS, $2, $4); }
- | WITH expr ';' expr_function
- { $$ = new ExprWith(CUR_POS, $2, $4); }
- | LET binds IN expr_function
- { if (!$2->dynamicAttrs.empty())
- throw ParseError({
- .msg = hintfmt("dynamic attributes not allowed in let"),
- .errPos = data->state.positions[CUR_POS]
- });
- $$ = new ExprLet($2, $4);
- }
- | expr_if
- ;
-
-expr_if
- : IF expr THEN expr ELSE expr { $$ = new ExprIf(CUR_POS, $2, $4, $6); }
- | expr_op
- ;
-
-expr_op
- : '!' expr_op %prec NOT { $$ = new ExprOpNot($2); }
- | '-' expr_op %prec NEGATE { $$ = new ExprCall(CUR_POS, new ExprVar(data->symbols.create("__sub")), {new ExprInt(0), $2}); }
- | expr_op EQ expr_op { $$ = new ExprOpEq($1, $3); }
- | expr_op NEQ expr_op { $$ = new ExprOpNEq($1, $3); }
- | expr_op '<' expr_op { $$ = new ExprCall(makeCurPos(@2, data), new ExprVar(data->symbols.create("__lessThan")), {$1, $3}); }
- | expr_op LEQ expr_op { $$ = new ExprOpNot(new ExprCall(makeCurPos(@2, data), new ExprVar(data->symbols.create("__lessThan")), {$3, $1})); }
- | expr_op '>' expr_op { $$ = new ExprCall(makeCurPos(@2, data), new ExprVar(data->symbols.create("__lessThan")), {$3, $1}); }
- | expr_op GEQ expr_op { $$ = new ExprOpNot(new ExprCall(makeCurPos(@2, data), new ExprVar(data->symbols.create("__lessThan")), {$1, $3})); }
- | expr_op AND expr_op { $$ = new ExprOpAnd(makeCurPos(@2, data), $1, $3); }
- | expr_op OR expr_op { $$ = new ExprOpOr(makeCurPos(@2, data), $1, $3); }
- | expr_op IMPL expr_op { $$ = new ExprOpImpl(makeCurPos(@2, data), $1, $3); }
- | expr_op UPDATE expr_op { $$ = new ExprOpUpdate(makeCurPos(@2, data), $1, $3); }
- | expr_op '?' attrpath { $$ = new ExprOpHasAttr($1, std::move(*$3)); delete $3; }
- | expr_op '+' expr_op
- { $$ = new ExprConcatStrings(makeCurPos(@2, data), false, new std::vector<std::pair<PosIdx, Expr *> >({{makeCurPos(@1, data), $1}, {makeCurPos(@3, data), $3}})); }
- | expr_op '-' expr_op { $$ = new ExprCall(makeCurPos(@2, data), new ExprVar(data->symbols.create("__sub")), {$1, $3}); }
- | expr_op '*' expr_op { $$ = new ExprCall(makeCurPos(@2, data), new ExprVar(data->symbols.create("__mul")), {$1, $3}); }
- | expr_op '/' expr_op { $$ = new ExprCall(makeCurPos(@2, data), new ExprVar(data->symbols.create("__div")), {$1, $3}); }
- | expr_op CONCAT expr_op { $$ = new ExprOpConcatLists(makeCurPos(@2, data), $1, $3); }
- | expr_app
- ;
-
-expr_app
- : expr_app expr_select {
- if (auto e2 = dynamic_cast<ExprCall *>($1)) {
- e2->args.push_back($2);
- $$ = $1;
- } else
- $$ = new ExprCall(CUR_POS, $1, {$2});
- }
- | expr_select
- ;
-
-expr_select
- : expr_simple '.' attrpath
- { $$ = new ExprSelect(CUR_POS, $1, std::move(*$3), nullptr); delete $3; }
- | expr_simple '.' attrpath OR_KW expr_select
- { $$ = new ExprSelect(CUR_POS, $1, std::move(*$3), $5); delete $3; }
- | /* Backwards compatibility: because Nixpkgs has a rarely used
- function named ‘or’, allow stuff like ‘map or [...]’. */
- expr_simple OR_KW
- { $$ = new ExprCall(CUR_POS, $1, {new ExprVar(CUR_POS, data->symbols.create("or"))}); }
- | expr_simple
- ;
-
-expr_simple
- : ID {
- std::string_view s = "__curPos";
- if ($1.l == s.size() && strncmp($1.p, s.data(), s.size()) == 0)
- $$ = new ExprPos(CUR_POS);
- else
- $$ = new ExprVar(CUR_POS, data->symbols.create($1));
- }
- | INT { $$ = new ExprInt($1); }
- | FLOAT { $$ = new ExprFloat($1); }
- | '"' string_parts '"' { $$ = $2; }
- | IND_STRING_OPEN ind_string_parts IND_STRING_CLOSE {
- $$ = stripIndentation(CUR_POS, data->symbols, std::move(*$2));
- delete $2;
- }
- | path_start PATH_END
- | path_start string_parts_interpolated PATH_END {
- $2->insert($2->begin(), {makeCurPos(@1, data), $1});
- $$ = new ExprConcatStrings(CUR_POS, false, $2);
- }
- | SPATH {
- std::string path($1.p + 1, $1.l - 2);
- $$ = new ExprCall(CUR_POS,
- new ExprVar(data->symbols.create("__findFile")),
- {new ExprVar(data->symbols.create("__nixPath")),
- new ExprString(std::move(path))});
- }
- | URI {
- static bool noURLLiterals = experimentalFeatureSettings.isEnabled(Xp::NoUrlLiterals);
- if (noURLLiterals)
- throw ParseError({
- .msg = hintfmt("URL literals are disabled"),
- .errPos = data->state.positions[CUR_POS]
- });
- $$ = new ExprString(std::string($1));
- }
- | '(' expr ')' { $$ = $2; }
- /* Let expressions `let {..., body = ...}' are just desugared
- into `(rec {..., body = ...}).body'. */
- | LET '{' binds '}'
- { $3->recursive = true; $$ = new ExprSelect(noPos, $3, data->symbols.create("body")); }
- | REC '{' binds '}'
- { $3->recursive = true; $$ = $3; }
- | '{' binds '}'
- { $$ = $2; }
- | '[' expr_list ']' { $$ = $2; }
- ;
-
-string_parts
- : STR { $$ = new ExprString(std::string($1)); }
- | string_parts_interpolated { $$ = new ExprConcatStrings(CUR_POS, true, $1); }
- | { $$ = new ExprString(""); }
- ;
-
-string_parts_interpolated
- : string_parts_interpolated STR
- { $$ = $1; $1->emplace_back(makeCurPos(@2, data), new ExprString(std::string($2))); }
- | string_parts_interpolated DOLLAR_CURLY expr '}' { $$ = $1; $1->emplace_back(makeCurPos(@2, data), $3); }
- | DOLLAR_CURLY expr '}' { $$ = new std::vector<std::pair<PosIdx, Expr *>>; $$->emplace_back(makeCurPos(@1, data), $2); }
- | STR DOLLAR_CURLY expr '}' {
- $$ = new std::vector<std::pair<PosIdx, Expr *>>;
- $$->emplace_back(makeCurPos(@1, data), new ExprString(std::string($1)));
- $$->emplace_back(makeCurPos(@2, data), $3);
- }
- ;
-
-path_start
- : PATH {
- Path path(absPath({$1.p, $1.l}, data->basePath.path.abs()));
- /* add back in the trailing '/' to the first segment */
- if ($1.p[$1.l-1] == '/' && $1.l > 1)
- path += "/";
- $$ = new ExprPath(std::move(path));
- }
- | HPATH {
- if (evalSettings.pureEval) {
- throw Error(
- "the path '%s' can not be resolved in pure mode",
- std::string_view($1.p, $1.l)
- );
- }
- Path path(getHome() + std::string($1.p + 1, $1.l - 1));
- $$ = new ExprPath(std::move(path));
- }
- ;
-
-ind_string_parts
- : ind_string_parts IND_STR { $$ = $1; $1->emplace_back(makeCurPos(@2, data), $2); }
- | ind_string_parts DOLLAR_CURLY expr '}' { $$ = $1; $1->emplace_back(makeCurPos(@2, data), $3); }
- | { $$ = new std::vector<std::pair<PosIdx, std::variant<Expr *, StringToken>>>; }
- ;
-
-binds
- : binds attrpath '=' expr ';' { $$ = $1; addAttr($$, std::move(*$2), $4, makeCurPos(@2, data), data->state); delete $2; }
- | binds INHERIT attrs ';'
- { $$ = $1;
- for (auto & i : *$3) {
- if ($$->attrs.find(i.symbol) != $$->attrs.end())
- dupAttr(data->state, i.symbol, makeCurPos(@3, data), $$->attrs[i.symbol].pos);
- auto pos = makeCurPos(@3, data);
- $$->attrs.emplace(i.symbol, ExprAttrs::AttrDef(new ExprVar(CUR_POS, i.symbol), pos, true));
- }
- delete $3;
- }
- | binds INHERIT '(' expr ')' attrs ';'
- { $$ = $1;
- /* !!! Should ensure sharing of the expression in $4. */
- for (auto & i : *$6) {
- if ($$->attrs.find(i.symbol) != $$->attrs.end())
- dupAttr(data->state, i.symbol, makeCurPos(@6, data), $$->attrs[i.symbol].pos);
- $$->attrs.emplace(i.symbol, ExprAttrs::AttrDef(new ExprSelect(CUR_POS, $4, i.symbol), makeCurPos(@6, data)));
- }
- delete $6;
- }
- | { $$ = new ExprAttrs(makeCurPos(@0, data)); }
- ;
-
-attrs
- : attrs attr { $$ = $1; $1->push_back(AttrName(data->symbols.create($2))); }
- | attrs string_attr
- { $$ = $1;
- ExprString * str = dynamic_cast<ExprString *>($2);
- if (str) {
- $$->push_back(AttrName(data->symbols.create(str->s)));
- delete str;
- } else
- throw ParseError({
- .msg = hintfmt("dynamic attributes not allowed in inherit"),
- .errPos = data->state.positions[makeCurPos(@2, data)]
- });
- }
- | { $$ = new AttrPath; }
- ;
-
-attrpath
- : attrpath '.' attr { $$ = $1; $1->push_back(AttrName(data->symbols.create($3))); }
- | attrpath '.' string_attr
- { $$ = $1;
- ExprString * str = dynamic_cast<ExprString *>($3);
- if (str) {
- $$->push_back(AttrName(data->symbols.create(str->s)));
- delete str;
- } else
- $$->push_back(AttrName($3));
- }
- | attr { $$ = new std::vector<AttrName>; $$->push_back(AttrName(data->symbols.create($1))); }
- | string_attr
- { $$ = new std::vector<AttrName>;
- ExprString *str = dynamic_cast<ExprString *>($1);
- if (str) {
- $$->push_back(AttrName(data->symbols.create(str->s)));
- delete str;
- } else
- $$->push_back(AttrName($1));
- }
- ;
-
-attr
- : ID
- | OR_KW { $$ = {"or", 2}; }
- ;
-
-string_attr
- : '"' string_parts '"' { $$ = $2; }
- | DOLLAR_CURLY expr '}' { $$ = $2; }
- ;
-
-expr_list
- : expr_list expr_select { $$ = $1; $1->elems.push_back($2); /* !!! dangerous */ }
- | { $$ = new ExprList; }
- ;
-
-formals
- : formal ',' formals
- { $$ = $3; $$->formals.emplace_back(*$1); delete $1; }
- | formal
- { $$ = new ParserFormals; $$->formals.emplace_back(*$1); $$->ellipsis = false; delete $1; }
- |
- { $$ = new ParserFormals; $$->ellipsis = false; }
- | ELLIPSIS
- { $$ = new ParserFormals; $$->ellipsis = true; }
- ;
-
-formal
- : ID { $$ = new Formal{CUR_POS, data->symbols.create($1), 0}; }
- | ID '?' expr { $$ = new Formal{CUR_POS, data->symbols.create($1), $3}; }
- ;
-
-%%
-
-
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <fcntl.h>
-#include <unistd.h>
-
-#include "eval.hh"
-#include "filetransfer.hh"
-#include "fetchers.hh"
-#include "store-api.hh"
-#include "flake/flake.hh"
-
-
-namespace nix {
-
-unsigned long Expr::nrExprs = 0;
-
-Expr * EvalState::parse(
- char * text,
- size_t length,
- Pos::Origin origin,
- const SourcePath & basePath,
- std::shared_ptr<StaticEnv> & staticEnv)
-{
- yyscan_t scanner;
- ParseData data {
- .state = *this,
- .symbols = symbols,
- .basePath = basePath,
- .origin = {origin},
- };
-
- yylex_init(&scanner);
- yy_scan_buffer(text, length, scanner);
- int res = yyparse(scanner, &data);
- yylex_destroy(scanner);
-
- if (res) throw ParseError(data.error.value());
-
- data.result->bindVars(*this, staticEnv);
-
- return data.result;
-}
-
-
-SourcePath resolveExprPath(const SourcePath & path)
-{
- /* If `path' is a symlink, follow it. This is so that relative
- path references work. */
- auto path2 = path.resolveSymlinks();
-
- /* If `path' refers to a directory, append `/default.nix'. */
- if (path2.lstat().type == InputAccessor::tDirectory)
- return path2 + "default.nix";
-
- return path2;
-}
-
-
-Expr * EvalState::parseExprFromFile(const SourcePath & path)
-{
- return parseExprFromFile(path, staticBaseEnv);
-}
-
-
-Expr * EvalState::parseExprFromFile(const SourcePath & path, std::shared_ptr<StaticEnv> & staticEnv)
-{
- auto buffer = path.readFile();
- // readFile hopefully have left some extra space for terminators
- buffer.append("\0\0", 2);
- return parse(buffer.data(), buffer.size(), Pos::Origin(path), path.parent(), staticEnv);
-}
-
-
-Expr * EvalState::parseExprFromString(std::string s_, const SourcePath & basePath, std::shared_ptr<StaticEnv> & staticEnv)
-{
- auto s = make_ref<std::string>(std::move(s_));
- s->append("\0\0", 2);
- return parse(s->data(), s->size(), Pos::String{.source = s}, basePath, staticEnv);
-}
-
-
-Expr * EvalState::parseExprFromString(std::string s, const SourcePath & basePath)
-{
- return parseExprFromString(std::move(s), basePath, staticBaseEnv);
-}
-
-
-Expr * EvalState::parseStdin()
-{
- //Activity act(*logger, lvlTalkative, "parsing standard input");
- auto buffer = drainFD(0);
- // drainFD should have left some extra space for terminators
- buffer.append("\0\0", 2);
- auto s = make_ref<std::string>(std::move(buffer));
- return parse(s->data(), s->size(), Pos::Stdin{.source = s}, rootPath(CanonPath::fromCwd()), staticBaseEnv);
-}
-
-
-SourcePath EvalState::findFile(const std::string_view path)
-{
- return findFile(searchPath, path);
-}
-
-
-SourcePath EvalState::findFile(const SearchPath & searchPath, const std::string_view path, const PosIdx pos)
-{
- for (auto & i : searchPath.elements) {
- auto suffixOpt = i.prefix.suffixIfPotentialMatch(path);
-
- if (!suffixOpt) continue;
- auto suffix = *suffixOpt;
-
- auto rOpt = resolveSearchPathPath(i.path);
- if (!rOpt) continue;
- auto r = *rOpt;
-
- Path res = suffix == "" ? r : concatStrings(r, "/", suffix);
- if (pathExists(res)) return CanonPath(canonPath(res));
- }
-
- if (hasPrefix(path, "nix/"))
- return CanonPath(concatStrings(corepkgsPrefix, path.substr(4)));
-
- debugThrow(ThrownError({
- .msg = hintfmt(evalSettings.pureEval
- ? "cannot look up '<%s>' in pure evaluation mode (use '--impure' to override)"
- : "file '%s' was not found in the Nix search path (add it using $NIX_PATH or -I)",
- path),
- .errPos = positions[pos]
- }), 0, 0);
-}
-
-
-std::optional<std::string> EvalState::resolveSearchPathPath(const SearchPath::Path & value0)
-{
- auto & value = value0.s;
- auto i = searchPathResolved.find(value);
- if (i != searchPathResolved.end()) return i->second;
-
- std::optional<std::string> res;
-
- if (EvalSettings::isPseudoUrl(value)) {
- try {
- auto storePath = fetchers::downloadTarball(
- store, EvalSettings::resolvePseudoUrl(value), "source", false).tree.storePath;
- res = { store->toRealPath(storePath) };
- } catch (FileTransferError & e) {
- logWarning({
- .msg = hintfmt("Nix search path entry '%1%' cannot be downloaded, ignoring", value)
- });
- res = std::nullopt;
- }
- }
-
- else if (hasPrefix(value, "flake:")) {
- experimentalFeatureSettings.require(Xp::Flakes);
- auto flakeRef = parseFlakeRef(value.substr(6), {}, true, false);
- debug("fetching flake search path element '%s''", value);
- auto storePath = flakeRef.resolve(store).fetchTree(store).first.storePath;
- res = { store->toRealPath(storePath) };
- }
-
- else {
- auto path = absPath(value);
- if (pathExists(path))
- res = { path };
- else {
- logWarning({
- .msg = hintfmt("Nix search path entry '%1%' does not exist, ignoring", value)
- });
- res = std::nullopt;
- }
- }
-
- if (res)
- debug("resolved search path element '%s' to '%s'", value, *res);
- else
- debug("failed to resolve search path element '%s'", value);
-
- searchPathResolved[value] = res;
- return res;
-}
-
-
-}
diff --git a/src/libexpr/parser/epilogue.inc b/src/libexpr/parser/epilogue.inc
new file mode 100644
index 00000000000..8e396a6f4ca
--- /dev/null
+++ b/src/libexpr/parser/epilogue.inc
@@ -0,0 +1,177 @@
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#include <fcntl.h>
+#include <unistd.h>
+
+#include "parser-tab.hh"
+#include "lexer-tab.hh"
+
+#include "eval.hh"
+#include "fetchers.hh"
+#include "filetransfer.hh"
+#include "flake/flake.hh"
+#include "store-api.hh"
+
+namespace nix {
+
+unsigned long Expr::nrExprs = 0;
+
+Expr * EvalState::parse(
+ char * text, size_t length, Pos::Origin origin, const SourcePath & basePath, std::shared_ptr<StaticEnv> & staticEnv)
+{
+ yyscan_t scanner;
+ ParseData data{
+ .state = *this,
+ .symbols = symbols,
+ .basePath = basePath,
+ .origin = {origin},
+ };
+
+ yylex_init(&scanner);
+ yy_scan_buffer(text, length, scanner);
+ yyparse(scanner, &data);
+ yylex_destroy(scanner);
+
+ data.diags.checkRaise(data.state.positions);
+
+ data.result->bindVars(*this, staticEnv);
+
+ return data.result;
+}
+
+SourcePath resolveExprPath(const SourcePath & path)
+{
+ /* If `path' is a symlink, follow it. This is so that relative
+ path references work. */
+ auto path2 = path.resolveSymlinks();
+
+ /* If `path' refers to a directory, append `/default.nix'. */
+ if (path2.lstat().type == InputAccessor::tDirectory)
+ return path2 + "default.nix";
+
+ return path2;
+}
+
+Expr * EvalState::parseExprFromFile(const SourcePath & path)
+{
+ return parseExprFromFile(path, staticBaseEnv);
+}
+
+Expr * EvalState::parseExprFromFile(const SourcePath & path, std::shared_ptr<StaticEnv> & staticEnv)
+{
+ auto buffer = path.readFile();
+ // readFile hopefully have left some extra space for terminators
+ buffer.append("\0\0", 2);
+ return parse(buffer.data(), buffer.size(), Pos::Origin(path), path.parent(), staticEnv);
+}
+
+Expr *
+EvalState::parseExprFromString(std::string s_, const SourcePath & basePath, std::shared_ptr<StaticEnv> & staticEnv)
+{
+ auto s = make_ref<std::string>(std::move(s_));
+ s->append("\0\0", 2);
+ return parse(s->data(), s->size(), Pos::String{.source = s}, basePath, staticEnv);
+}
+
+Expr * EvalState::parseExprFromString(std::string s, const SourcePath & basePath)
+{
+ return parseExprFromString(std::move(s), basePath, staticBaseEnv);
+}
+
+Expr * EvalState::parseStdin()
+{
+ // Activity act(*logger, lvlTalkative, "parsing standard input");
+ auto buffer = drainFD(0);
+ // drainFD should have left some extra space for terminators
+ buffer.append("\0\0", 2);
+ auto s = make_ref<std::string>(std::move(buffer));
+ return parse(s->data(), s->size(), Pos::Stdin{.source = s}, rootPath(CanonPath::fromCwd()), staticBaseEnv);
+}
+
+SourcePath EvalState::findFile(const std::string_view path)
+{
+ return findFile(searchPath, path);
+}
+
+SourcePath EvalState::findFile(const SearchPath & searchPath, const std::string_view path, const PosIdx pos)
+{
+ for (const auto & i : searchPath.elements) {
+ auto suffixOpt = i.prefix.suffixIfPotentialMatch(path);
+
+ if (!suffixOpt)
+ continue;
+ auto suffix = *suffixOpt;
+
+ auto rOpt = resolveSearchPathPath(i.path);
+ if (!rOpt)
+ continue;
+ auto r = *rOpt;
+
+ Path res = suffix.empty() ? r : concatStrings(r, "/", suffix);
+ if (pathExists(res))
+ return CanonPath(canonPath(res));
+ }
+
+ if (hasPrefix(path, "nix/"))
+ return CanonPath(concatStrings(corepkgsPrefix, path.substr(4)));
+
+ debugThrow(
+ ThrownError(
+ {.msg = hintfmt(
+ evalSettings.pureEval
+ ? "cannot look up '<%s>' in pure evaluation mode (use '--impure' to override)"
+ : "file '%s' was not found in the Nix search path (add it using $NIX_PATH or -I)",
+ path),
+ .errPos = positions[pos]}),
+ nullptr, nullptr);
+}
+
+std::optional<std::string> EvalState::resolveSearchPathPath(const SearchPath::Path & value0)
+{
+ const auto & value = value0.s;
+ auto i = searchPathResolved.find(value);
+ if (i != searchPathResolved.end())
+ return i->second;
+
+ std::optional<std::string> res;
+
+ if (EvalSettings::isPseudoUrl(value)) {
+ try {
+ auto storePath =
+ fetchers::downloadTarball(store, EvalSettings::resolvePseudoUrl(value), "source", false).tree.storePath;
+ res = {store->toRealPath(storePath)};
+ } catch (FileTransferError & e) {
+ logWarning({.msg = hintfmt("Nix search path entry '%1%' cannot be downloaded, ignoring", value)});
+ res = std::nullopt;
+ }
+ }
+
+ else if (hasPrefix(value, "flake:")) {
+ experimentalFeatureSettings.require(Xp::Flakes);
+ auto flakeRef = parseFlakeRef(value.substr(6), {}, true, false);
+ debug("fetching flake search path element '%s''", value);
+ auto storePath = flakeRef.resolve(store).fetchTree(store).first.storePath;
+ res = {store->toRealPath(storePath)};
+ }
+
+ else {
+ auto path = absPath(value);
+ if (pathExists(path))
+ res = {path};
+ else {
+ logWarning({.msg = hintfmt("Nix search path entry '%1%' does not exist, ignoring", value)});
+ res = std::nullopt;
+ }
+ }
+
+ if (res)
+ debug("resolved search path element '%s' to '%s'", value, *res);
+ else
+ debug("failed to resolve search path element '%s'", value);
+
+ searchPathResolved[value] = res;
+ return res;
+}
+
+} // namespace nix
diff --git a/src/libexpr/parser/parser.y b/src/libexpr/parser/parser.y
new file mode 100644
index 00000000000..1fc9abc536b
--- /dev/null
+++ b/src/libexpr/parser/parser.y
@@ -0,0 +1,339 @@
+%glr-parser
+%define api.pure
+%locations
+%define parse.error verbose
+%defines
+/* %no-lines */
+%parse-param { void * scanner }
+%parse-param { nix::ParseData * data }
+%lex-param { void * scanner }
+%lex-param { nix::ParseData * data }
+%expect 1
+%expect-rr 1
+
+%code requires {
+#include "parser/requires.hh"
+}
+%{
+#include "parser/prologue.inc"
+%}
+
+%union {
+ // !!! We're probably leaking stuff here.
+ nix::Expr * e;
+ nix::ExprList * list;
+ nix::ExprAttrs * attrs;
+ nix::ParserFormals * formals;
+ nix::Formal * formal;
+ nix::NixInt n;
+ nix::NixFloat nf;
+ StringToken id; // !!! -> Symbol
+ StringToken path;
+ StringToken uri;
+ StringToken str;
+ std::vector<nix::AttrName> * attrNames;
+ std::vector<std::pair<nix::PosIdx, nix::Expr *>> * string_parts;
+ std::vector<std::pair<nix::PosIdx, std::variant<nix::Expr *, StringToken>>> * ind_string_parts;
+}
+
+%type <e> start expr expr_function expr_if expr_op
+%type <e> expr_select expr_simple expr_app
+%type <list> expr_list
+%type <attrs> binds
+%type <formals> formals
+%type <formal> formal
+%type <attrNames> attrs attrpath
+%type <string_parts> string_parts_interpolated
+%type <ind_string_parts> ind_string_parts
+%type <e> path_start string_parts string_attr
+%type <id> attr
+%token <id> ID
+%token <str> STR IND_STR
+%token <n> INT
+%token <nf> FLOAT
+%token <path> PATH HPATH SPATH PATH_END
+%token <uri> URI
+%token IF THEN ELSE ASSERT WITH LET IN REC INHERIT EQ NEQ AND OR IMPL OR_KW
+%token DOLLAR_CURLY /* == ${ */
+%token IND_STRING_OPEN IND_STRING_CLOSE
+%token ELLIPSIS
+
+%right IMPL
+%left OR
+%left AND
+%nonassoc EQ NEQ
+%nonassoc '<' '>' LEQ GEQ
+%right UPDATE
+%left NOT
+%left '+' '-'
+%left '*' '/'
+%right CONCAT
+%nonassoc '?'
+%nonassoc NEGATE
+
+%%
+
+start: expr { data->result = $1; };
+
+expr: expr_function;
+
+expr_function
+ : ID ':' expr_function
+ { $$ = new ExprLambda(CUR_POS, data->symbols.create($1), 0, $3); }
+ | '{' formals '}' ':' expr_function
+ { $$ = new ExprLambda(CUR_POS, toFormals(*data, $2), $5); }
+ | '{' formals '}' '@' ID ':' expr_function
+ {
+ auto arg = data->symbols.create($5);
+ $$ = new ExprLambda(CUR_POS, arg, toFormals(*data, $2, CUR_POS, arg), $7);
+ }
+ | ID '@' '{' formals '}' ':' expr_function
+ {
+ auto arg = data->symbols.create($1);
+ $$ = new ExprLambda(CUR_POS, arg, toFormals(*data, $4, CUR_POS, arg), $7);
+ }
+ | ASSERT expr ';' expr_function
+ { $$ = new ExprAssert(CUR_POS, $2, $4); }
+ | WITH expr ';' expr_function
+ { $$ = new ExprWith(CUR_POS, $2, $4); }
+ | LET binds IN expr_function
+ {
+ if (!$2->dynamicAttrs.empty()) {
+ data->diags.add(std::make_unique<DiagDynamicInLet>(CUR_POS));
+ }
+ $$ = new ExprLet($2, $4);
+ }
+ | expr_if
+ ;
+
+expr_if
+ : IF expr THEN expr ELSE expr { $$ = new ExprIf(CUR_POS, $2, $4, $6); }
+ | expr_op
+ ;
+
+expr_op
+ : '!' expr_op %prec NOT { $$ = new ExprOpNot($2); }
+ | '-' expr_op %prec NEGATE { $$ = new ExprCall(CUR_POS, new ExprVar(data->symbols.create("__sub")), {new ExprInt(0), $2}); }
+ | expr_op EQ expr_op { $$ = new ExprOpEq($1, $3); }
+ | expr_op NEQ expr_op { $$ = new ExprOpNEq($1, $3); }
+ | expr_op '<' expr_op { $$ = new ExprCall(makeCurPos(@2, data), new ExprVar(data->symbols.create("__lessThan")), {$1, $3}); }
+ | expr_op LEQ expr_op { $$ = new ExprOpNot(new ExprCall(makeCurPos(@2, data), new ExprVar(data->symbols.create("__lessThan")), {$3, $1})); }
+ | expr_op '>' expr_op { $$ = new ExprCall(makeCurPos(@2, data), new ExprVar(data->symbols.create("__lessThan")), {$3, $1}); }
+ | expr_op GEQ expr_op { $$ = new ExprOpNot(new ExprCall(makeCurPos(@2, data), new ExprVar(data->symbols.create("__lessThan")), {$1, $3})); }
+ | expr_op AND expr_op { $$ = new ExprOpAnd(makeCurPos(@2, data), $1, $3); }
+ | expr_op OR expr_op { $$ = new ExprOpOr(makeCurPos(@2, data), $1, $3); }
+ | expr_op IMPL expr_op { $$ = new ExprOpImpl(makeCurPos(@2, data), $1, $3); }
+ | expr_op UPDATE expr_op { $$ = new ExprOpUpdate(makeCurPos(@2, data), $1, $3); }
+ | expr_op '?' attrpath { $$ = new ExprOpHasAttr($1, std::move(*$3)); delete $3; }
+ | expr_op '+' expr_op
+ { $$ = new ExprConcatStrings(makeCurPos(@2, data), false, new std::vector<std::pair<PosIdx, Expr *> >({{makeCurPos(@1, data), $1}, {makeCurPos(@3, data), $3}})); }
+ | expr_op '-' expr_op { $$ = new ExprCall(makeCurPos(@2, data), new ExprVar(data->symbols.create("__sub")), {$1, $3}); }
+ | expr_op '*' expr_op { $$ = new ExprCall(makeCurPos(@2, data), new ExprVar(data->symbols.create("__mul")), {$1, $3}); }
+ | expr_op '/' expr_op { $$ = new ExprCall(makeCurPos(@2, data), new ExprVar(data->symbols.create("__div")), {$1, $3}); }
+ | expr_op CONCAT expr_op { $$ = new ExprOpConcatLists(makeCurPos(@2, data), $1, $3); }
+ | expr_app
+ ;
+
+expr_app
+ : expr_app expr_select {
+ if (auto e2 = dynamic_cast<ExprCall *>($1)) {
+ e2->args.push_back($2);
+ $$ = $1;
+ } else
+ $$ = new ExprCall(CUR_POS, $1, {$2});
+ }
+ | expr_select
+ ;
+
+expr_select
+ : expr_simple '.' attrpath
+ { $$ = new ExprSelect(CUR_POS, $1, std::move(*$3), nullptr); delete $3; }
+ | expr_simple '.' attrpath OR_KW expr_select
+ { $$ = new ExprSelect(CUR_POS, $1, std::move(*$3), $5); delete $3; }
+ | /* Backwards compatibility: because Nixpkgs has a rarely used
+ function named ‘or’, allow stuff like ‘map or [...]’. */
+ expr_simple OR_KW
+ { $$ = new ExprCall(CUR_POS, $1, {new ExprVar(CUR_POS, data->symbols.create("or"))}); }
+ | expr_simple
+ ;
+
+expr_simple
+ : ID {
+ std::string_view s = "__curPos";
+ if ($1.l == s.size() && strncmp($1.p, s.data(), s.size()) == 0)
+ $$ = new ExprPos(CUR_POS);
+ else
+ $$ = new ExprVar(CUR_POS, data->symbols.create($1));
+ }
+ | INT { $$ = new ExprInt($1); }
+ | FLOAT { $$ = new ExprFloat($1); }
+ | '"' string_parts '"' { $$ = $2; }
+ | IND_STRING_OPEN ind_string_parts IND_STRING_CLOSE {
+ $$ = stripIndentation(CUR_POS, data->symbols, std::move(*$2));
+ delete $2;
+ }
+ | path_start PATH_END
+ | path_start string_parts_interpolated PATH_END {
+ $2->insert($2->begin(), {makeCurPos(@1, data), $1});
+ $$ = new ExprConcatStrings(CUR_POS, false, $2);
+ }
+ | SPATH {
+ std::string path($1.p + 1, $1.l - 2);
+ $$ = new ExprCall(CUR_POS,
+ new ExprVar(data->symbols.create("__findFile")),
+ {new ExprVar(data->symbols.create("__nixPath")),
+ new ExprString(std::move(path))});
+ }
+ | URI {
+ data->diags.add(std::make_unique<DiagURLLiteral>(CUR_POS));
+ $$ = new ExprString(std::string($1));
+ }
+ | '(' expr ')' { $$ = $2; }
+ /* Let expressions `let {..., body = ...}' are just desugared
+ into `(rec {..., body = ...}).body'. */
+ | LET '{' binds '}'
+ { $3->recursive = true; $$ = new ExprSelect(noPos, $3, data->symbols.create("body")); }
+ | REC '{' binds '}'
+ { $3->recursive = true; $$ = $3; }
+ | '{' binds '}'
+ { $$ = $2; }
+ | '[' expr_list ']' { $$ = $2; }
+ ;
+
+string_parts
+ : STR { $$ = new ExprString(std::string($1)); }
+ | string_parts_interpolated { $$ = new ExprConcatStrings(CUR_POS, true, $1); }
+ | { $$ = new ExprString(""); }
+ ;
+
+string_parts_interpolated
+ : string_parts_interpolated STR
+ { $$ = $1; $1->emplace_back(makeCurPos(@2, data), new ExprString(std::string($2))); }
+ | string_parts_interpolated DOLLAR_CURLY expr '}' { $$ = $1; $1->emplace_back(makeCurPos(@2, data), $3); }
+ | DOLLAR_CURLY expr '}' { $$ = new std::vector<std::pair<PosIdx, Expr *>>; $$->emplace_back(makeCurPos(@1, data), $2); }
+ | STR DOLLAR_CURLY expr '}' {
+ $$ = new std::vector<std::pair<PosIdx, Expr *>>;
+ $$->emplace_back(makeCurPos(@1, data), new ExprString(std::string($1)));
+ $$->emplace_back(makeCurPos(@2, data), $3);
+ }
+ ;
+
+path_start
+ : PATH {
+ Path path(absPath({$1.p, $1.l}, data->basePath.path.abs()));
+ /* add back in the trailing '/' to the first segment */
+ if ($1.p[$1.l-1] == '/' && $1.l > 1)
+ path += "/";
+ $$ = new ExprPath(std::move(path));
+ }
+ | HPATH {
+ if (evalSettings.pureEval) {
+ data->diags.add(std::make_unique<DiagHPath>(CUR_POS));
+ }
+ Path path(getHome() + std::string($1.p + 1, $1.l - 1));
+ $$ = new ExprPath(std::move(path));
+ }
+ ;
+
+ind_string_parts
+ : ind_string_parts IND_STR { $$ = $1; $1->emplace_back(makeCurPos(@2, data), $2); }
+ | ind_string_parts DOLLAR_CURLY expr '}' { $$ = $1; $1->emplace_back(makeCurPos(@2, data), $3); }
+ | { $$ = new std::vector<std::pair<PosIdx, std::variant<Expr *, StringToken>>>; }
+ ;
+
+binds
+ : binds attrpath '=' expr ';' { $$ = $1; addAttr($$, std::move(*$2), $4, makeCurPos(@2, data), data->state); delete $2; }
+ | binds INHERIT attrs ';'
+ { $$ = $1;
+ for (auto & i : *$3) {
+ if ($$->attrs.find(i.symbol) != $$->attrs.end())
+ dupAttr(data->state, i.symbol, makeCurPos(@3, data), $$->attrs[i.symbol].pos);
+ auto pos = makeCurPos(@3, data);
+ $$->attrs.emplace(i.symbol, ExprAttrs::AttrDef(new ExprVar(CUR_POS, i.symbol), pos, true));
+ }
+ delete $3;
+ }
+ | binds INHERIT '(' expr ')' attrs ';'
+ { $$ = $1;
+ /* !!! Should ensure sharing of the expression in $4. */
+ for (auto & i : *$6) {
+ if ($$->attrs.find(i.symbol) != $$->attrs.end())
+ dupAttr(data->state, i.symbol, makeCurPos(@6, data), $$->attrs[i.symbol].pos);
+ $$->attrs.emplace(i.symbol, ExprAttrs::AttrDef(new ExprSelect(CUR_POS, $4, i.symbol), makeCurPos(@6, data)));
+ }
+ delete $6;
+ }
+ | { $$ = new ExprAttrs(makeCurPos(@0, data)); }
+ ;
+
+attrs
+ : attrs attr { $$ = $1; $1->push_back(AttrName(data->symbols.create($2))); }
+ | attrs string_attr
+ { $$ = $1;
+ ExprString * str = dynamic_cast<ExprString *>($2);
+ if (str) {
+ $$->push_back(AttrName(data->symbols.create(str->s)));
+ delete str;
+ } else
+ data->diags.add(std::make_unique<DiagInheritDynamic>(CUR_POS));
+ }
+ | { $$ = new AttrPath; }
+ ;
+
+attrpath
+ : attrpath '.' attr { $$ = $1; $1->push_back(AttrName(data->symbols.create($3))); }
+ | attrpath '.' string_attr
+ { $$ = $1;
+ ExprString * str = dynamic_cast<ExprString *>($3);
+ if (str) {
+ $$->push_back(AttrName(data->symbols.create(str->s)));
+ delete str;
+ } else
+ $$->push_back(AttrName($3));
+ }
+ | attr { $$ = new std::vector<AttrName>; $$->push_back(AttrName(data->symbols.create($1))); }
+ | string_attr
+ { $$ = new std::vector<AttrName>;
+ ExprString *str = dynamic_cast<ExprString *>($1);
+ if (str) {
+ $$->push_back(AttrName(data->symbols.create(str->s)));
+ delete str;
+ } else
+ $$->push_back(AttrName($1));
+ }
+ ;
+
+attr
+ : ID
+ | OR_KW { $$ = {"or", 2}; }
+ ;
+
+string_attr
+ : '"' string_parts '"' { $$ = $2; }
+ | DOLLAR_CURLY expr '}' { $$ = $2; }
+ ;
+
+expr_list
+ : expr_list expr_select { $$ = $1; $1->elems.push_back($2); /* !!! dangerous */ }
+ | { $$ = new ExprList; }
+ ;
+
+formals
+ : formal ',' formals
+ { $$ = $3; $$->formals.emplace_back(*$1); delete $1; }
+ | formal
+ { $$ = new ParserFormals; $$->formals.emplace_back(*$1); $$->ellipsis = false; delete $1; }
+ |
+ { $$ = new ParserFormals; $$->ellipsis = false; }
+ | ELLIPSIS
+ { $$ = new ParserFormals; $$->ellipsis = true; }
+ ;
+
+formal
+ : ID { $$ = new Formal{CUR_POS, data->symbols.create($1), 0}; }
+ | ID '?' expr { $$ = new Formal{CUR_POS, data->symbols.create($1), $3}; }
+ ;
+
+%%
+
+#include "parser/epilogue.inc"
diff --git a/src/libexpr/parser/prologue.inc b/src/libexpr/parser/prologue.inc
new file mode 100644
index 00000000000..a89122bd208
--- /dev/null
+++ b/src/libexpr/parser/prologue.inc
@@ -0,0 +1,233 @@
+#include "diagnostic.hh"
+#include "parser-tab.hh"
+#include "lexer-tab.hh"
+
+YY_DECL;
+
+using namespace nix;
+
+namespace nix {
+
+static void dupAttr(const EvalState & state, const AttrPath & attrPath, const PosIdx pos, const PosIdx prevPos)
+{
+ throw ParseError(
+ {.msg = hintfmt(
+ "attribute '%1%' already defined at %2%", showAttrPath(state.symbols, attrPath), state.positions[prevPos]),
+ .errPos = state.positions[pos]});
+}
+
+static void dupAttr(const EvalState & state, Symbol attr, const PosIdx pos, const PosIdx prevPos)
+{
+ throw ParseError(
+ {.msg = hintfmt("attribute '%1%' already defined at %2%", state.symbols[attr], state.positions[prevPos]),
+ .errPos = state.positions[pos]});
+}
+
+static void addAttr(ExprAttrs * attrs, AttrPath && attrPath, Expr * e, const PosIdx pos, const nix::EvalState & state)
+{
+ AttrPath::iterator i;
+ // All attrpaths have at least one attr
+ assert(!attrPath.empty());
+ // Checking attrPath validity.
+ // ===========================
+ for (i = attrPath.begin(); i + 1 < attrPath.end(); i++) {
+ if (i->symbol) {
+ auto j = attrs->attrs.find(i->symbol);
+ if (j != attrs->attrs.end()) {
+ if (!j->second.inherited) {
+ auto * attrs2 = dynamic_cast<ExprAttrs *>(j->second.e);
+ if (!attrs2)
+ dupAttr(state, attrPath, pos, j->second.pos);
+ attrs = attrs2;
+ } else
+ dupAttr(state, attrPath, pos, j->second.pos);
+ } else {
+ auto * nested = new ExprAttrs;
+ attrs->attrs[i->symbol] = ExprAttrs::AttrDef(nested, pos);
+ attrs = nested;
+ }
+ } else {
+ auto * nested = new ExprAttrs;
+ attrs->dynamicAttrs.push_back(ExprAttrs::DynamicAttrDef(i->expr, nested, pos));
+ attrs = nested;
+ }
+ }
+ // Expr insertion.
+ // ==========================
+ if (i->symbol) {
+ auto j = attrs->attrs.find(i->symbol);
+ if (j != attrs->attrs.end()) {
+ // This attr path is already defined. However, if both
+ // e and the expr pointed by the attr path are two attribute sets,
+ // we want to merge them.
+ // Otherwise, throw an error.
+ auto * ae = dynamic_cast<ExprAttrs *>(e);
+ auto * jAttrs = dynamic_cast<ExprAttrs *>(j->second.e);
+ if (jAttrs && ae) {
+ for (auto & ad : ae->attrs) {
+ auto j2 = jAttrs->attrs.find(ad.first);
+ if (j2 != jAttrs->attrs.end()) // Attr already defined in iAttrs, error.
+ dupAttr(state, ad.first, j2->second.pos, ad.second.pos);
+ jAttrs->attrs.emplace(ad.first, ad.second);
+ }
+ jAttrs->dynamicAttrs.insert(
+ jAttrs->dynamicAttrs.end(), ae->dynamicAttrs.begin(), ae->dynamicAttrs.end());
+ } else {
+ dupAttr(state, attrPath, pos, j->second.pos);
+ }
+ } else {
+ // This attr path is not defined. Let's create it.
+ attrs->attrs.emplace(i->symbol, ExprAttrs::AttrDef(e, pos));
+ e->setName(i->symbol);
+ }
+ } else {
+ attrs->dynamicAttrs.push_back(ExprAttrs::DynamicAttrDef(i->expr, e, pos));
+ }
+}
+
+static Formals * toFormals(ParseData & data, ParserFormals * formals, PosIdx pos = noPos, Symbol arg = {})
+{
+ std::sort(formals->formals.begin(), formals->formals.end(), [](const auto & a, const auto & b) {
+ return std::tie(a.name, a.pos) < std::tie(b.name, b.pos);
+ });
+
+ std::optional<std::pair<Symbol, PosIdx>> duplicate;
+ for (size_t i = 0; i + 1 < formals->formals.size(); i++) {
+ if (formals->formals[i].name != formals->formals[i + 1].name)
+ continue;
+ std::pair thisDup{formals->formals[i].name, formals->formals[i + 1].pos};
+ duplicate = std::min(thisDup, duplicate.value_or(thisDup));
+ }
+ if (duplicate)
+ throw ParseError(
+ {.msg = hintfmt("duplicate formal function argument '%1%'", data.symbols[duplicate->first]),
+ .errPos = data.state.positions[duplicate->second]});
+
+ Formals result;
+ result.ellipsis = formals->ellipsis;
+ result.formals = std::move(formals->formals);
+
+ if (arg && result.has(arg))
+ throw ParseError(
+ {.msg = hintfmt("duplicate formal function argument '%1%'", data.symbols[arg]),
+ .errPos = data.state.positions[pos]});
+
+ delete formals;
+ return new Formals(std::move(result));
+}
+
+static Expr * stripIndentation(
+ const PosIdx pos, SymbolTable & symbols, std::vector<std::pair<PosIdx, std::variant<Expr *, StringToken>>> && es)
+{
+ if (es.empty())
+ return new ExprString("");
+
+ /* Figure out the minimum indentation. Note that by design
+ whitespace-only final lines are not taken into account. (So
+ the " " in "\n ''" is ignored, but the " " in "\n foo''" is.) */
+ bool atStartOfLine = true; /* = seen only whitespace in the current line */
+ size_t minIndent = 1000000;
+ size_t curIndent = 0;
+ for (auto & [i_pos, i] : es) {
+ auto * str = std::get_if<StringToken>(&i);
+ if (!str || !str->hasIndentation) {
+ /* Anti-quotations and escaped characters end the current start-of-line whitespace. */
+ if (atStartOfLine) {
+ atStartOfLine = false;
+ if (curIndent < minIndent)
+ minIndent = curIndent;
+ }
+ continue;
+ }
+ for (size_t j = 0; j < str->l; ++j) {
+ if (atStartOfLine) {
+ if (str->p[j] == ' ')
+ curIndent++;
+ else if (str->p[j] == '\n') {
+ /* Empty line, doesn't influence minimum
+ indentation. */
+ curIndent = 0;
+ } else {
+ atStartOfLine = false;
+ if (curIndent < minIndent)
+ minIndent = curIndent;
+ }
+ } else if (str->p[j] == '\n') {
+ atStartOfLine = true;
+ curIndent = 0;
+ }
+ }
+ }
+
+ /* Strip spaces from each line. */
+ auto * es2 = new std::vector<std::pair<PosIdx, Expr *>>;
+ atStartOfLine = true;
+ size_t curDropped = 0;
+ size_t n = es.size();
+ auto i = es.begin();
+ const auto trimExpr = [&](Expr * e) {
+ atStartOfLine = false;
+ curDropped = 0;
+ es2->emplace_back(i->first, e);
+ };
+ const auto trimString = [&](const StringToken & t) {
+ std::string s2;
+ for (size_t j = 0; j < t.l; ++j) {
+ if (atStartOfLine) {
+ if (t.p[j] == ' ') {
+ if (curDropped++ >= minIndent)
+ s2 += t.p[j];
+ } else if (t.p[j] == '\n') {
+ curDropped = 0;
+ s2 += t.p[j];
+ } else {
+ atStartOfLine = false;
+ curDropped = 0;
+ s2 += t.p[j];
+ }
+ } else {
+ s2 += t.p[j];
+ if (t.p[j] == '\n')
+ atStartOfLine = true;
+ }
+ }
+
+ /* Remove the last line if it is empty and consists only of
+ spaces. */
+ if (n == 1) {
+ std::string::size_type p = s2.find_last_of('\n');
+ if (p != std::string::npos && s2.find_first_not_of(' ', p + 1) == std::string::npos)
+ s2 = std::string(s2, 0, p + 1);
+ }
+
+ es2->emplace_back(i->first, new ExprString(std::move(s2)));
+ };
+ for (; i != es.end(); ++i, --n) {
+ std::visit(overloaded{trimExpr, trimString}, i->second);
+ }
+
+ /* If this is a single string, then don't do a concatenation. */
+ if (es2->size() == 1 && dynamic_cast<ExprString *>((*es2)[0].second)) {
+ auto * const result = (*es2)[0].second;
+ delete es2;
+ return result;
+ }
+ return new ExprConcatStrings(pos, true, es2);
+}
+
+static inline PosIdx makeCurPos(const YYLTYPE & loc, ParseData * data)
+{
+ return data->state.positions.add(data->origin, loc.first_line, loc.first_column);
+}
+
+#define CUR_POS makeCurPos(*yylocp, data)
+
+} // namespace nix
+
+void yyerror(YYLTYPE * loc, yyscan_t scanner, ParseData * data, const char * error)
+{
+ DiagBisonParse diag;
+ diag.err = error;
+ diag.loc = makeCurPos(*loc, data);
+ data->diags.add(std::make_unique<DiagBisonParse>(std::move(diag)));
+}
diff --git a/src/libexpr/parser/requires.hh b/src/libexpr/parser/requires.hh
new file mode 100644
index 00000000000..9a13ee9f583
--- /dev/null
+++ b/src/libexpr/parser/requires.hh
@@ -0,0 +1,55 @@
+
+#ifndef BISON_HEADER
+#define BISON_HEADER
+
+#include <variant>
+
+#include "diagnostic.hh"
+#include "util.hh"
+
+#include "nixexpr.hh"
+#include "eval.hh"
+#include "eval-settings.hh"
+#include "eval.hh"
+#include "globals.hh"
+#include "nixexpr.hh"
+#include "util.hh"
+
+namespace nix {
+
+struct ParseData
+{
+ EvalState & state;
+ SymbolTable & symbols;
+ Expr * result;
+ SourcePath basePath;
+ PosTable::Origin origin;
+
+ /// Stores diagnostics while parsing this input
+ DiagnosticEngine diags;
+};
+
+struct ParserFormals
+{
+ std::vector<Formal> formals;
+ bool ellipsis = false;
+};
+
+} // namespace nix
+
+// using C a struct allows us to avoid having to define the special
+// members that using string_view here would implicitly delete.
+struct StringToken
+{
+ const char * p;
+ size_t l;
+ bool hasIndentation;
+ operator std::string_view() const
+ {
+ return {p, l};
+ }
+};
+
+#define YY_DECL int yylex(YYSTYPE * yylval_param, YYLTYPE * yylloc_param, yyscan_t yyscanner, nix::ParseData * data)
+
+#endif // BISON_HEADER