From 3e6aafd236ffe1ea76c252e1b264a9fb7b15a8e7 Mon Sep 17 00:00:00 2001
From: Aditya Toshniwal <aditya.toshniwal@enterprisedb.com>
Date: Mon, 9 Dec 2019 19:25:42 +0530
Subject: [PATCH] [sql mode] Support  backslash and escape constants in pgsql

Add support for escape constant as mentioned here:
https://www.postgresql.org/docs/current/sql-syntax-lexical.html#SQL-SYNTAX-STRINGS-ESCAPE
---
 mode/sql/sql.js | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/mode/sql/sql.js b/mode/sql/sql.js
index 35902bbab1..6f3e328593 100644
--- a/mode/sql/sql.js
+++ b/mode/sql/sql.js
@@ -65,6 +65,12 @@ CodeMirror.defineMode("sql", function(config, parserConfig) {
       // charset casting: _utf8'str', N'str', n'str'
       // ref: http://dev.mysql.com/doc/refman/5.5/en/string-literals.html
       return "keyword";
+    } else if (support.escapeConstant && (ch == "e" || ch == "E")
+        && (stream.peek() == "'" || (stream.peek() == '"' && support.doubleQuote))) {
+      // escape constant: E'str', e'str'
+      // ref: https://www.postgresql.org/docs/current/sql-syntax-lexical.html#SQL-SYNTAX-STRINGS-ESCAPE
+      state.tokenize = tokenLiteral(stream.peek(), true);
+      return "keyword";
     } else if (support.commentSlashSlash && ch == "/" && stream.eat("/")) {
       // 1-line comment
       stream.skipToEnd();
@@ -122,15 +128,19 @@ CodeMirror.defineMode("sql", function(config, parserConfig) {
   }
 
   // 'string', with char specified in quote escaped by '\'
-  function tokenLiteral(quote) {
+  function tokenLiteral(quote, withEscapeConst) {
     return function(stream, state) {
       var escaped = false, ch;
+      /* eat the first quote in case of escape constant */
+      if(withEscapeConst) {
+        ch = stream.eat(quote)
+      }
       while ((ch = stream.next()) != null) {
         if (ch == quote && !escaped) {
           state.tokenize = tokenBase;
           break;
         }
-        escaped = backslashStringEscapes && !escaped && ch == "\\";
+        escaped = (backslashStringEscapes || withEscapeConst) && !escaped && ch == "\\";
       }
       return "string";
     };
@@ -413,8 +423,9 @@ CodeMirror.defineMode("sql", function(config, parserConfig) {
     builtin: set("bigint int8 bigserial serial8 bit varying varbit boolean bool box bytea character char varchar cidr circle date double precision float8 inet integer int int4 interval json jsonb line lseg macaddr macaddr8 money numeric decimal path pg_lsn point polygon real float4 smallint int2 smallserial serial2 serial serial4 text time without zone with timetz timestamp timestamptz tsquery tsvector txid_snapshot uuid xml"),
     atoms: set("false true null unknown"),
     operatorChars: /^[*\/+\-%<>!=&|^\/#@?~]/,
+    backslashStringEscapes: false,
     dateSQL: set("date time timestamp"),
-    support: set("ODBCdotTable decimallessFloat zerolessFloat binaryNumber hexNumber nCharCast charsetCast")
+    support: set("ODBCdotTable decimallessFloat zerolessFloat binaryNumber hexNumber nCharCast charsetCast escapeConstant")
   });
 
   // Google's SQL-like query language, GQL