(wip) vaev-style: Added support for dynamic property registration.

Author: sleepy-monax

src/vaev-engine/css/lexer.cpp

@@ -65,7 +65,7 @@ export struct Token {
     }
 
     void repr(Io::Emit& e) const {
-        if (not *this) {
+        if (not*this) {
             e("nil");
             return;
         }
@@ -207,19 +207,21 @@ static auto const RE_NUMBER = Re::chain(
 
 export struct Lexer {
     Io::SScan _scan;
-    Token _curr;
 
     Lexer(Str text) : _scan(text) {
-        _curr = _next(_scan);
     }
 
     Lexer(Io::SScan const& scan)
         : _scan(scan) {
-        _curr = _next(_scan);
     }
 
-    Token peek() const {
-        return _curr;
+    Token peek(usize offset = 1) const {
+        Io::SScan scan = _scan;
+        Token res = Token::NIL;
+        for (auto _ : range(offset)) {
+            res = _next(scan);
+        }
+        return res;
     }
 
     Token _nextIdent(Io::SScan& s) const {
@@ -392,9 +394,7 @@ export struct Lexer {
     }
 
     Token next() {
-        auto res = _curr;
-        _curr = _next(_scan);
-        return res;
+        return _next(_scan);
     }
 
     bool ended() const {

src/vaev-engine/css/parser.cpp

@@ -17,6 +17,11 @@ export struct Sst;
 
 export using Content = Vec<Sst>;
 
+export enum struct Important {
+    UNSET,
+    YES,
+};
+
 #define FOREACH_SST(SST) \
     SST(RULE)            \
     SST(FUNC)            \
@@ -40,13 +45,19 @@ export struct Sst {
     Token token = Token(Token::NIL);
     Opt<Box<Sst>> prefix{};
     Content content{};
+    Important important = Important::UNSET;
 
     Sst(Type type) : type(type) {}
 
     Sst(Token token) : type(TOKEN), token(token) {}
 
     Sst(Content content) : type(LIST), content(content) {}
 
+    // https://drafts.csswg.org/css-variables-2/#guaranteed-invalid
+    static Sst guaranteedInvalid() {
+        return Token::badString("");
+    }
+
     void repr(Io::Emit& e) const {
         if (type == TOKEN) {
             e("{}", token);
@@ -200,18 +211,48 @@ Sst consumeAtRule(Lexer& lex) {
     }
 }
 
-export Content consumeDeclarationValue(Lexer& lex) {
+Important consumeImportant(Lexer& lex) {
+    if (lex.peek() != Css::Token::delim("!"))
+        return Important::UNSET;
+    lex.next();
+
+    auto copy = lex;
+    eatWhitespace(copy);
+    if (copy.next() != Css::Token::ident("important"))
+        return Important::UNSET;
+    lex = copy;
+    return Important::YES;
+}
+
+export bool endedDeclarationValue(Lexer& lex) {
+    return lex.peek() == Token::END_OF_FILE or
+           lex.peek() == Token::SEMICOLON or
+           lex.peek() == Token::RIGHT_CURLY_BRACKET;
+}
+
+export Tuple<Content, Important> consumeDeclarationValue(Lexer& lex) {
     Content value;
+
     // 3. While the next input token is a <whitespace-token>, consume the next input token.
     eatWhitespace(lex);
 
     // 4. As long as the next input token is anything other than an <EOF-token>,
     //    consume a component value and append it to the declaration’s value.
-    while ((lex.peek() != Token::END_OF_FILE and lex.peek() != Token::SEMICOLON and lex.peek() != Token::RIGHT_CURLY_BRACKET)) {
-        value.pushBack(consumeComponentValue(lex));
-        eatWhitespace(lex);
+    while (endedDeclarationValue(lex)) {
+        // 5. If the last two non-<whitespace-token>s in the declaration’s
+        //    value are a <delim-token> with the value "!" followed by an
+        //    <ident-token> with a value that is an ASCII case-insensitive match
+        //    for "important", remove them from the declaration’s value
+        //    and set the declaration’s important flag to true.
+        if (consumeImportant(lex) == Important::YES) {
+            eatWhitespace(lex);
+            return {std::move(value), Important::UNSET};
+        } else {
+            value.pushBack(consumeComponentValue(lex));
+            eatWhitespace(lex);
+        }
     }
-    return value;
+    return {std::move(value), Important::UNSET};
 }
 
 // https://www.w3.org/TR/css-syntax-3/#consume-style-block
@@ -286,6 +327,7 @@ Content consumeDeclarationBlock(Lexer& lex) {
     return res;
 }
 
+// https://www.w3.org/TR/css-syntax-3/#consume-declaration
 export Opt<Sst> consumeDeclaration(Lexer& lex) {
     Sst decl{Sst::DECL};
     decl.token = lex.next();
@@ -303,7 +345,9 @@ export Opt<Sst> consumeDeclaration(Lexer& lex) {
     lex.next();
 
     // Parse the declaration’s value.
-    decl.content = consumeDeclarationValue(lex);
+    auto [content, important] = consumeDeclarationValue(lex);
+    decl.content = std::move(content);
+    decl.important = important;
 
     return decl;
 }

src/vaev-engine/manifest.json

@@ -12,6 +12,7 @@
         "layout/base",
         "layout/builder",
         "loader",
+        "props",
         "style",
         "values",
         "xml"