From c718d1ab103b307594e660928679a308c6ed36b6 Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Thu, 16 Jul 2015 12:11:49 +0200
Subject: [PATCH] Ignore double negative in `Lexer_getNumber` (issue 6218)

Basic mathematics would suggest that a double negative should always become positive, but it appears that Adobe Reader simply ignores that case. Hence I think that it makes sense for us to do the same.

Fixes 6218.
---
 src/core/parser.js       | 5 +++++
 test/unit/parser_spec.js | 7 +++++++
 2 files changed, 12 insertions(+)

diff --git a/src/core/parser.js b/src/core/parser.js
index 6c98b085a..62a2482d4 100644
--- a/src/core/parser.js
+++ b/src/core/parser.js
@@ -671,6 +671,11 @@ var Lexer = (function LexerClosure() {
       if (ch === 0x2D) { // '-'
         sign = -1;
         ch = this.nextChar();
+
+        if (ch === 0x2D) { // '-'
+          // Ignore double negative (this is consistent with Adobe Reader).
+          ch = this.nextChar();
+        }
       } else if (ch === 0x2B) { // '+'
         ch = this.nextChar();
       }
diff --git a/test/unit/parser_spec.js b/test/unit/parser_spec.js
index 4fb9089e9..24e18de99 100644
--- a/test/unit/parser_spec.js
+++ b/test/unit/parser_spec.js
@@ -27,6 +27,13 @@ describe('parser', function() {
       }
     });
 
+    it('should ignore double negative before number', function() {
+      var input = new StringStream('--205.88');
+      var lexer = new Lexer(input);
+      var result = lexer.getNumber();
+
+      expect(result).toEqual(-205.88);
+    });
 
     it('should handle glued numbers and operators', function() {
       var input = new StringStream('123ET');