feat: add quoteIdentifier and quoteQualifiedIdentifier from PostgreSQL ruleutils.c

Port PostgreSQL's quote_identifier() and quote_qualified_identifier() functions
to TypeScript. These functions properly:
- Quote identifiers only when needed (lowercase letters, digits, underscores)
- Escape embedded double quotes as ""
- Check against keyword categories (quote all except UNRESERVED_KEYWORD)

References:
- https://github.com/postgres/postgres/blob/fab5cd3dd1323f9e66efeb676c4bb212ff340204/src/backend/utils/adt/ruleutils.c#L13055-L13137
- https://github.com/postgres/postgres/blob/fab5cd3dd1323f9e66efeb676c4bb212ff340204/src/backend/utils/adt/ruleutils.c#L13139-L13156

Co-Authored-By: Dan Lynch <[email protected]>

Author: devin-ai-integration[bot]

packages/deparser/src/utils/quote-utils.ts

@@ -1,4 +1,4 @@
-import { RESERVED_KEYWORDS, TYPE_FUNC_NAME_KEYWORDS } from '../kwlist';
+import { RESERVED_KEYWORDS, TYPE_FUNC_NAME_KEYWORDS, UNRESERVED_KEYWORDS, keywordKindOf } from '../kwlist';
 
 export class QuoteUtils {
   /**
@@ -105,5 +105,88 @@ export class QuoteUtils {
     // unless it's a raw \x... bytea-style literal.
     return !/^\\x[0-9a-fA-F]+$/i.test(value) && value.includes('\\');
   }
+
+  /**
+   * Quote an identifier only if needed
+   *
+   * This is a TypeScript port of PostgreSQL's quote_identifier() function from ruleutils.c
+   * https://github.com/postgres/postgres/blob/fab5cd3dd1323f9e66efeb676c4bb212ff340204/src/backend/utils/adt/ruleutils.c#L13055-L13137
+   *
+   * Can avoid quoting if ident starts with a lowercase letter or underscore
+   * and contains only lowercase letters, digits, and underscores, *and* is
+   * not any SQL keyword. Otherwise, supply quotes.
+   *
+   * When quotes are needed, embedded double quotes are properly escaped as "".
+   */
+  static quoteIdentifier(ident: string): string {
+    if (!ident) return ident;
+
+    let nquotes = 0;
+    let safe = true;
+
+    // Check first character: must be lowercase letter or underscore
+    const firstChar = ident[0];
+    if (!((firstChar >= 'a' && firstChar <= 'z') || firstChar === '_')) {
+      safe = false;
+    }
+
+    // Check all characters
+    for (let i = 0; i < ident.length; i++) {
+      const ch = ident[i];
+      if ((ch >= 'a' && ch <= 'z') ||
+          (ch >= '0' && ch <= '9') ||
+          (ch === '_')) {
+        // okay
+      } else {
+        safe = false;
+        if (ch === '"') {
+          nquotes++;
+        }
+      }
+    }
+
+    if (safe) {
+      // Check for keyword. We quote keywords except for unreserved ones.
+      // (In some cases we could avoid quoting a col_name or type_func_name
+      // keyword, but it seems much harder than it's worth to tell that.)
+      const kwKind = keywordKindOf(ident);
+      if (kwKind !== 'NO_KEYWORD' && kwKind !== 'UNRESERVED_KEYWORD') {
+        safe = false;
+      }
+    }
+
+    if (safe) {
+      return ident; // no change needed
+    }
+
+    // Build quoted identifier with escaped embedded quotes
+    let result = '"';
+    for (let i = 0; i < ident.length; i++) {
+      const ch = ident[i];
+      if (ch === '"') {
+        result += '"'; // escape " as ""
+      }
+      result += ch;
+    }
+    result += '"';
+
+    return result;
+  }
+
+  /**
+   * Quote a possibly-qualified identifier
+   *
+   * This is a TypeScript port of PostgreSQL's quote_qualified_identifier() function from ruleutils.c
+   * https://github.com/postgres/postgres/blob/fab5cd3dd1323f9e66efeb676c4bb212ff340204/src/backend/utils/adt/ruleutils.c#L13139-L13156
+   *
+   * Return a name of the form qualifier.ident, or just ident if qualifier
+   * is null/undefined, quoting each component if necessary.
+   */
+  static quoteQualifiedIdentifier(qualifier: string | null | undefined, ident: string): string {
+    if (qualifier) {
+      return `${QuoteUtils.quoteIdentifier(qualifier)}.${QuoteUtils.quoteIdentifier(ident)}`;
+    }
+    return QuoteUtils.quoteIdentifier(ident);
+  }
 
 }