Fixed leading whitespace before interpolation in simple strings

lib/coffee-script/lexer.js

@@ -166,30 +166,25 @@
     };
 
     Lexer.prototype.stringToken = function() {
-      var match, octalEsc, string;
-      switch (this.chunk.charAt(0)) {
+      var octalEsc, quote, string, trimmed;
+      switch (quote = this.chunk.charAt(0)) {
         case "'":
-          if (!(match = SIMPLESTR.exec(this.chunk))) {
-            return 0;
-          }
-          string = match[0];
-          this.token('STRING', this.escapeLines(string), 0, string.length);
+          string = SIMPLESTR.exec(this.chunk)[0];
           break;
         case '"':
-          if (!(string = this.balancedString(this.chunk, '"'))) {
-            return 0;
-          }
-          if (0 < string.indexOf('#{', 1)) {
-            this.interpolateString(string.slice(1, -1), {
-              strOffset: 1,
-              lexedLength: string.length
-            });
-          } else {
-            this.token('STRING', this.escapeLines(string), 0, string.length);
-          }
-          break;
-        default:
-          return 0;
+          string = this.balancedString(this.chunk, '"');
+      }
+      if (!string) {
+        return 0;
+      }
+      trimmed = this.removeNewlines(string.slice(1, -1));
+      if (quote === '"' && 0 < string.indexOf('#{', 1)) {
+        this.interpolateString(trimmed, {
+          strOffset: 1,
+          lexedLength: string.length
+        });
+      } else {
+        this.token('STRING', quote + this.escapeLines(trimmed) + quote, 0, string.length);
       }
       if (octalEsc = /^(?:\\.|[^\\])*\\(?:0[0-7]|[1-7])/.test(string)) {
         this.error("octal escape sequences " + string + " are not allowed");
@@ -763,6 +758,10 @@
       return LINE_CONTINUER.test(this.chunk) || ((_ref2 = this.tag()) === '\\' || _ref2 === '.' || _ref2 === '?.' || _ref2 === '?::' || _ref2 === 'UNARY' || _ref2 === 'MATH' || _ref2 === '+' || _ref2 === '-' || _ref2 === 'SHIFT' || _ref2 === 'RELATION' || _ref2 === 'COMPARE' || _ref2 === 'LOGIC' || _ref2 === 'THROW' || _ref2 === 'EXTENDS');
     };
 
+    Lexer.prototype.removeNewlines = function(str) {
+      return str.replace(/^\s*\n\s*/, '').replace(/([^\\]|\\\\)\s*\n\s*$/, '$1');
+    };
+
     Lexer.prototype.escapeLines = function(str, heredoc) {
       str = str.replace(/\\[^\S\n]*(\n|\\)\s*/g, function(escaped, character) {
         if (character === '\n') {
@@ -774,7 +773,7 @@
       if (heredoc) {
         return str.replace(MULTILINER, '\\n');
       } else {
-        return str.replace(/^(.)\s*\n\s*/, '$1').replace(/\s*\n\s*(.)$/, '$1').replace(/\s*\n\s*/g, ' ');
+        return str.replace(/\s*\n\s*/g, ' ');
       }
     };
 

src/lexer.coffee

@@ -186,19 +186,15 @@ exports.Lexer = class Lexer
   # Matches strings, including multi-line strings. Ensures that quotation marks
   # are balanced within the string's contents, and within nested interpolations.
   stringToken: ->
-    switch @chunk.charAt 0
-      when "'"
-        return 0 unless match = SIMPLESTR.exec @chunk
-        string = match[0]
-        @token 'STRING', @escapeLines(string), 0, string.length
-      when '"'
-        return 0 unless string = @balancedString @chunk, '"'
-        if 0 < string.indexOf '#{', 1
-          @interpolateString string[1...-1], strOffset: 1, lexedLength: string.length
-        else
-          @token 'STRING', @escapeLines(string), 0, string.length
-      else
-        return 0
+    switch quote = @chunk.charAt 0
+      when "'" then [string] = SIMPLESTR.exec @chunk
+      when '"' then string = @balancedString @chunk, '"'
+    return 0 unless string
+    trimmed = @removeNewlines string[1...-1]
+    if quote is '"' and 0 < string.indexOf '#{', 1
+      @interpolateString trimmed, strOffset: 1, lexedLength: string.length
+    else
+      @token 'STRING', quote + @escapeLines(trimmed) + quote, 0, string.length
     if octalEsc = /^(?:\\.|[^\\])*\\(?:0[0-7]|[1-7])/.test string
       @error "octal escape sequences #{string} are not allowed"
     string.length
@@ -686,6 +682,11 @@ exports.Lexer = class Lexer
     @tag() in ['\\', '.', '?.', '?::', 'UNARY', 'MATH', '+', '-', 'SHIFT', 'RELATION'
                'COMPARE', 'LOGIC', 'THROW', 'EXTENDS']
 
+  # Remove newlines from beginning and (non escaped) from end of string literals.
+  removeNewlines: (str) ->
+    str.replace(/^\s*\n\s*/, '')
+       .replace(/([^\\]|\\\\)\s*\n\s*$/, '$1')
+
   # Converts newlines for string literals.
   escapeLines: (str, heredoc) ->
     # Ignore escaped backslashes and remove escaped newlines
@@ -695,9 +696,7 @@ exports.Lexer = class Lexer
       str.replace MULTILINER, '\\n'
     else
       # Trim leading and trailing whitespace, string includes quotes
-      str.replace(/^(.)\s*\n\s*/, '$1')
-         .replace(/\s*\n\s*(.)$/, '$1')
-         .replace(/\s*\n\s*/g, ' ')
+      str.replace /\s*\n\s*/g, ' '
 
   # Constructs a string token by escaping quotes and newlines.
   makeString: (body, quote, heredoc) ->

test/strings.coffee

@@ -81,6 +81,9 @@ test "#3229, multiline strings", ->
     'string ' + "inside
                  interpolation"
     }", "a string inside interpolation"
+  eq "
+      #{1}
+     ", '1'
 
   # Handle escaped backslashes correctly.
   eq '\\', `'\\'`
@@ -155,6 +158,11 @@ test "#3249, escape newlines in heredocs with backslashes", ->
         too #{3}\
     !
   """, 'interpolation 1\n  follows 2  too 3!'
+  eq """
+
+    #{1} #{2}
+
+    """, '\n1 2\n'
 
   # TODO: uncomment when #2388 is fixed
   # eq """a heredoc #{