feat: implement automatic E-prefix detection for escaped string literals

- Add needsEscapePrefix() method to detect backslash escape sequences
- Enhance A_Const and String methods to automatically add E-prefix when needed
- Support common escape patterns: \n, \t, \r, \b, \f, \, \', \x, \u, \U, octal
- Properly escape backslashes and quotes in E-prefixed strings
- Avoid E-prefix for hexadecimal bytea literals to prevent conflicts
- All 251 test suites pass with 264 total tests

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

Author: devin-ai-integration[bot]

packages/deparser/src/deparser.ts

@@ -1254,18 +1254,46 @@ export class Deparser implements DeparserVisitor {
     } else if (nodeAny.sval !== undefined) {
       if (typeof nodeAny.sval === 'object' && nodeAny.sval !== null) {
         if (nodeAny.sval.sval !== undefined) {
-          return QuoteUtils.escape(nodeAny.sval.sval);
+          const value = nodeAny.sval.sval;
+          const needsEscape = this.needsEscapePrefix(value);
+          if (needsEscape) {
+            const escapedValue = value.replace(/\\/g, '\\\\').replace(/'/g, "''");
+            return `E'${escapedValue}'`;
+          } else {
+            return QuoteUtils.escape(value);
+          }
         } else if (nodeAny.sval.String && nodeAny.sval.String.sval !== undefined) {
-          return QuoteUtils.escape(nodeAny.sval.String.sval);
+          const value = nodeAny.sval.String.sval;
+          const needsEscape = this.needsEscapePrefix(value);
+          if (needsEscape) {
+            const escapedValue = value.replace(/\\/g, '\\\\').replace(/'/g, "''");
+            return `E'${escapedValue}'`;
+          } else {
+            return QuoteUtils.escape(value);
+          }
         } else if (Object.keys(nodeAny.sval).length === 0) {
           return "''";
         } else {
-          return QuoteUtils.escape(nodeAny.sval.toString());
+          const value = nodeAny.sval.toString();
+          const needsEscape = this.needsEscapePrefix(value);
+          if (needsEscape) {
+            const escapedValue = value.replace(/\\/g, '\\\\').replace(/'/g, "''");
+            return `E'${escapedValue}'`;
+          } else {
+            return QuoteUtils.escape(value);
+          }
         }
       } else if (nodeAny.sval === null) {
         return 'NULL';
       } else {
-        return QuoteUtils.escape(nodeAny.sval);
+        const value = nodeAny.sval;
+        const needsEscape = this.needsEscapePrefix(value);
+        if (needsEscape) {
+          const escapedValue = value.replace(/\\/g, '\\\\').replace(/'/g, "''");
+          return `E'${escapedValue}'`;
+        } else {
+          return QuoteUtils.escape(value);
+        }
       }
     } else if (nodeAny.boolval !== undefined) {
       if (typeof nodeAny.boolval === 'object' && nodeAny.boolval !== null) {
@@ -2014,9 +2042,34 @@ export class Deparser implements DeparserVisitor {
     return caseMap[defName.toLowerCase()] || defName;
   }
 
+  needsEscapePrefix(value: string): boolean {
+    // Don't add E-prefix to hexadecimal bytea literals (e.g., \xDeAdBeEf)
+    if (/^\\x[0-9a-fA-F]+$/i.test(value)) {
+      return false;
+    }
+    
+    // Don't add E-prefix to strings that look like bytea literals with mixed content
+    if (/\\x[0-9a-fA-F]/.test(value) && !/\\[nrtbf\\']/.test(value)) {
+      return false;
+    }
+    
+    // Check for common backslash escape sequences that require E-prefix
+    return /\\[nrtbf\\']/.test(value) ||             // Basic escapes: \n, \t, \r, \b, \f, \\, \'
+           /\\u[0-9a-fA-F]{4}/.test(value) ||        // Unicode escapes: \u0041
+           /\\U[0-9a-fA-F]{8}/.test(value) ||        // Extended unicode escapes: \U00000041
+           /\\[0-7]{1,3}/.test(value);               // Octal escapes: \123
+  }
+
   String(node: t.String, context: DeparserContext): string {
     if (context.isStringLiteral || context.isEnumValue) {
-      return `'${node.sval || ''}'`;
+      const value = node.sval || '';
+      const needsEscape = this.needsEscapePrefix(value);
+      if (needsEscape) {
+        const escapedValue = value.replace(/\\/g, '\\\\').replace(/'/g, "''");
+        return `E'${escapedValue}'`;
+      } else {
+        return QuoteUtils.escape(value);
+      }
     }
 
     const value = node.sval || '';