From 9bd3cca7c4bc241bb7144d7c836dcb164c153491 Mon Sep 17 00:00:00 2001
From: Jeremy Ashkenas <jashkenas@gmail.com>
Date: Wed, 8 Sep 2010 22:46:13 -0400
Subject: [PATCH] Introducing the notion of 'indebt' to mirror 'outdebt', but
 for suppressed indentation with trailing operators etc. Issue #639.

---
 lib/lexer.js        |  7 +++++--
 src/lexer.coffee    | 12 ++++++++----
 test/test_if.coffee | 10 ++++++++++
 3 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/lib/lexer.js b/lib/lexer.js
index 3949d0ea..7095ed3d 100644
--- a/lib/lexer.js
+++ b/lib/lexer.js
@@ -26,6 +26,7 @@
       this.i = 0;
       this.line = o.line || 0;
       this.indent = 0;
+      this.indebt = 0;
       this.outdebt = 0;
       this.indents = [];
       this.tokens = [];
@@ -245,20 +246,22 @@
       size = indent.match(LAST_DENTS).reverse()[0].match(LAST_DENT)[1].length;
       nextCharacter = this.match(NEXT_CHARACTER, 1);
       noNewlines = nextCharacter === '.' || nextCharacter === ',' || this.unfinished();
-      if (size === this.indent) {
+      if (size - this.indebt === this.indent) {
         if (noNewlines) {
           return this.suppressNewlines();
         }
         return this.newlineToken(indent);
       } else if (size > this.indent) {
         if (noNewlines) {
+          this.indebt = size - this.indent;
           return this.suppressNewlines();
         }
         diff = size - this.indent + this.outdebt;
         this.token('INDENT', diff);
         this.indents.push(diff);
-        this.outdebt = 0;
+        this.outdebt = (this.indebt = 0);
       } else {
+        this.indebt = 0;
         this.outdentToken(this.indent - size, noNewlines);
       }
       this.indent = size;
diff --git a/src/lexer.coffee b/src/lexer.coffee
index eec263a0..9344bffa 100644
--- a/src/lexer.coffee
+++ b/src/lexer.coffee
@@ -46,7 +46,8 @@ exports.Lexer = class Lexer
     @i       = 0            # Current character position we're parsing.
     @line    = o.line or 0  # The current line.
     @indent  = 0            # The current indentation level.
-    @outdebt = 0            # The under-outdentation of the last outdent.
+    @indebt  = 0            # The over-indentation at the current level.
+    @outdebt = 0            # The under-outdentation at the current level.
     @indents = []           # The stack of all current indentation levels.
     @tokens  = []           # Stream of parsed tokens in the form ['TYPE', value, line]
     while @i < @code.length
@@ -203,16 +204,19 @@ exports.Lexer = class Lexer
     size = indent.match(LAST_DENTS).reverse()[0].match(LAST_DENT)[1].length
     nextCharacter = @match NEXT_CHARACTER, 1
     noNewlines = nextCharacter is '.' or nextCharacter is ',' or @unfinished()
-    if size is @indent
+    if size - @indebt is @indent
       return @suppressNewlines() if noNewlines
       return @newlineToken indent
     else if size > @indent
-      return @suppressNewlines() if noNewlines
+      if noNewlines
+        @indebt = size - @indent
+        return @suppressNewlines()
       diff = size - @indent + @outdebt
       @token 'INDENT', diff
       @indents.push diff
-      @outdebt = 0
+      @outdebt = @indebt = 0
     else
+      @indebt = 0
       @outdentToken @indent - size, noNewlines
     @indent = size
     true
diff --git a/test/test_if.coffee b/test/test_if.coffee
index e22c5584..e00582e9 100644
--- a/test/test_if.coffee
+++ b/test/test_if.coffee
@@ -118,3 +118,13 @@ isTrue = (x) -> x is true
 if isTrue yes then i += 1
 
 ok i is 2
+
+# If/else with a suppressed indentation via assignment.
+result =
+  if      false then 10
+  else if no    then 20
+  else if 0     then 30
+  else if NaN   then 40
+  else               50
+
+ok result is 50