From b60b9ed06795393d55aff740d6e7a7d31016f06c Mon Sep 17 00:00:00 2001
From: Alan Pierce <alangpierce@gmail.com>
Date: Mon, 17 Oct 2016 20:44:47 -0700
Subject: [PATCH] fix: properly set location for string tokens ending in a
 newline

Fixes https://github.com/decaffeinate/decaffeinate/issues/457

The existing logic for computing the end location of a string was to take the
end of the string contents, then add the delimiter length to last_column. For
example, `"""abc"""` would have an end position three characters after the `c`.
However, if a string ended in a newline, then the end location for the string
contents would be one line above the end location for the string, so the proper
fix is to move the end location to the next line, not just to shift it to the
right.

This avoids a bug where the location data would sometimes reference a
non-existent location (one past the end of its line), which would confuse
decaffeinate-parser.
---
 lib/coffee-script/lexer.js |  7 ++++++-
 src/lexer.coffee           |  6 +++++-
 test/location.coffee       | 23 +++++++++++++++++++++++
 3 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/lib/coffee-script/lexer.js b/lib/coffee-script/lexer.js
index a9a3dd175d..0adce36d9c 100644
--- a/lib/coffee-script/lexer.js
+++ b/lib/coffee-script/lexer.js
@@ -644,7 +644,12 @@
       }
       firstToken = tokens[0], lastToken = tokens[tokens.length - 1];
       firstToken[2].first_column -= delimiter.length;
-      lastToken[2].last_column += delimiter.length;
+      if (lastToken[1].substr(-1) === '\n') {
+        lastToken[2].last_line += 1;
+        lastToken[2].last_column = delimiter.length - 1;
+      } else {
+        lastToken[2].last_column += delimiter.length;
+      }
       if (lastToken[1].length === 0) {
         lastToken[2].last_column -= 1;
       }
diff --git a/src/lexer.coffee b/src/lexer.coffee
index e38c22b1c6..79a8a6ad12 100644
--- a/src/lexer.coffee
+++ b/src/lexer.coffee
@@ -530,7 +530,11 @@ exports.Lexer = class Lexer
 
     [firstToken, ..., lastToken] = tokens
     firstToken[2].first_column -= delimiter.length
-    lastToken[2].last_column += delimiter.length
+    if lastToken[1].substr(-1) == '\n'
+      lastToken[2].last_line += 1
+      lastToken[2].last_column = delimiter.length - 1
+    else
+      lastToken[2].last_column += delimiter.length
     lastToken[2].last_column -= 1 if lastToken[1].length is 0
 
     {tokens, index: offsetInChunk + delimiter.length}
diff --git a/test/location.coffee b/test/location.coffee
index a2f855a7ba..efec69e9c1 100644
--- a/test/location.coffee
+++ b/test/location.coffee
@@ -528,6 +528,29 @@ test "Verify real CALL_END tokens have the right position", ->
   eq callEnd[2].first_column, startIndex + 2
   eq callEnd[2].last_column, startIndex + 2
 
+test "Verify normal heredocs have the right position", ->
+  source = '''
+    """
+    a"""
+  '''
+  [stringToken] = CoffeeScript.tokens source
+  eq stringToken[2].first_line, 0
+  eq stringToken[2].first_column, 0
+  eq stringToken[2].last_line, 1
+  eq stringToken[2].last_column, 3
+
+test "Verify heredocs ending with a newline have the right position", ->
+  source = '''
+    """
+    a
+    """
+  '''
+  [stringToken] = CoffeeScript.tokens source
+  eq stringToken[2].first_line, 0
+  eq stringToken[2].first_column, 0
+  eq stringToken[2].last_line, 2
+  eq stringToken[2].last_column, 2
+
 test "Verify all tokens get a location", ->
   doesNotThrow ->
     tokens = CoffeeScript.tokens testScript