fix: parse named redirects in zsh

.changeset/named-zsh-redirects.md

@@ -0,0 +1,5 @@
+---
+"@aliou/sh": patch
+---
+
+Parse named file descriptor redirects in Bash and Zsh.

src/parser/dialect.test.ts

@@ -49,6 +49,10 @@ describe("dialect enforcement: POSIX", () => {
     expectErr("foo <<< bar", "posix", /<<</);
   });
 
+  it("rejects named file descriptor redirects", () => {
+    expectErr("foo {fd}<f", "posix", /\{varname\}.*bash\/zsh feature/);
+  });
+
   it("rejects process substitution", () => {
     expectErr("diff <(foo) <(bar)", "posix", /process subst/);
   });
@@ -98,6 +102,10 @@ describe("dialect enforcement: mksh", () => {
   it("rejects ${!foo@}", () => {
     expectErr("echo ${!foo@}", "mksh", /\$\{!/);
   });
+
+  it("rejects named file descriptor redirects", () => {
+    expectErr("foo {fd}<f", "mksh", /\{varname\}.*bash\/zsh feature/);
+  });
 });
 
 describe("dialect enforcement: bash (default) accepts everything", () => {

src/parser/redirects.test.ts

@@ -66,6 +66,21 @@ describe("parse (phase 3: assignments and redirects)", () => {
       ),
     });
   });
+
+  it.each([
+    "bash",
+    "zsh",
+  ] as const)("parses named file descriptor redirects in %s", (dialect) => {
+    expect(parse("foo {fd}<f", { dialect })).toMatchAst({
+      ast: program(
+        stmt({
+          type: "SimpleCommand",
+          words: [word("foo")],
+          redirects: [redirect("<", "f", "{fd}")],
+        }),
+      ),
+    });
+  });
 });
 
 describe("parse (phase 12: extended redirects)", () => {

src/tokenizer/tokenize.ts

@@ -1,6 +1,13 @@
 import type { ParseOptions } from "../ast";
 import { checkLang } from "../dialect";
-import { isDigit, operatorChars, redirChars, symbolChars } from "./charsets";
+import {
+  isDigit,
+  isNameChar,
+  isNameStart,
+  operatorChars,
+  redirChars,
+  symbolChars,
+} from "./charsets";
 import { SourceMap } from "./cursor";
 import { scanBacktick } from "./scan-backtick";
 import { scanExpansion } from "./scan-expansion";
@@ -174,6 +181,32 @@ export function tokenize(source: string, options: ParseOptions = {}): Token[] {
       }
     }
 
+    if (ch === "{" && atBoundary && isNameStart(source.charAt(i + 1))) {
+      let j = i + 2;
+      while (j < source.length && isNameChar(source.charAt(j))) {
+        j += 1;
+      }
+      if (source.charAt(j) === "}") {
+        const redir = tryRedirOp(source, j + 1);
+        if (redir) {
+          checkLang(options.dialect, map.posAt(i), "`{varname}` redirects", [
+            "bash",
+            "zsh",
+          ]);
+          tokens.push({
+            type: "redir",
+            op: redir.op,
+            fd: source.slice(i, j + 1),
+            pos: map.posAt(i),
+            end: map.posAt(j + 1 + redir.len),
+          });
+          i = j + 1 + redir.len;
+          atBoundary = true;
+          continue;
+        }
+      }
+    }
+
     if (isDigit(ch)) {
       let j = i;
       while (j < source.length && isDigit(source.charAt(j))) {