1 files changed, 72 insertions, 0 deletions
diff --git a/packages/astro-parser/src/parse/read/context.ts b/packages/astro-parser/src/parse/read/context.ts
new file mode 100644
index 000000000..565c66d18
--- /dev/null
+++ b/packages/astro-parser/src/parse/read/context.ts
@@ -0,0 +1,72 @@
+// @ts-nocheck
+
+import { Parser } from '../index.js';
+import { isIdentifierStart } from 'acorn';
+import full_char_code_at from '../../utils/full_char_code_at.js';
+import { is_bracket_open, is_bracket_close, is_bracket_pair, get_bracket_close } from '../utils/bracket.js';
+import { parse_expression_at } from './expression.js';
+import { Pattern } from 'estree';
+
+export default function read_context(parser: Parser): Pattern & { start: number; end: number } {
+  const start = parser.index;
+  let i = parser.index;
+
+  const code = full_char_code_at(parser.template, i);
+  if (isIdentifierStart(code, true)) {
+    return {
+      type: 'Identifier',
+      name: parser.read_identifier(),
+      start,
+      end: parser.index,
+    };
+  }
+
+  if (!is_bracket_open(code)) {
+    parser.error({
+      code: 'unexpected-token',
+      message: 'Expected identifier or destructure pattern',
+    });
+  }
+
+  const bracket_stack = [code];
+  i += code <= 0xffff ? 1 : 2;
+
+  while (i < parser.template.length) {
+    const code = full_char_code_at(parser.template, i);
+    if (is_bracket_open(code)) {
+      bracket_stack.push(code);
+    } else if (is_bracket_close(code)) {
+      if (!is_bracket_pair(bracket_stack[bracket_stack.length - 1], code)) {
+        parser.error({
+          code: 'unexpected-token',
+          message: `Expected ${String.fromCharCode(get_bracket_close(bracket_stack[bracket_stack.length - 1]))}`,
+        });
+      }
+      bracket_stack.pop();
+      if (bracket_stack.length === 0) {
+        i += code <= 0xffff ? 1 : 2;
+        break;
+      }
+    }
+    i += code <= 0xffff ? 1 : 2;
+  }
+
+  parser.index = i;
+
+  const pattern_string = parser.template.slice(start, i);
+  try {
+    // the length of the `space_with_newline` has to be start - 1
+    // because we added a `(` in front of the pattern_string,
+    // which shifted the entire string to right by 1
+    // so we offset it by removing 1 character in the `space_with_newline`
+    // to achieve that, we remove the 1st space encountered,
+    // so it will not affect the `column` of the node
+    let space_with_newline = parser.template.slice(0, start).replace(/[^\n]/g, ' ');
+    const first_space = space_with_newline.indexOf(' ');
+    space_with_newline = space_with_newline.slice(0, first_space) + space_with_newline.slice(first_space + 1);
+
+    return (parse_expression_at(`${space_with_newline}(${pattern_string} = 1)`, start - 1) as any).left;
+  } catch (error) {
+    parser.acorn_error(error);
+  }
+}