Added string interpolation for identifiers

lib/lexer.js

@@ -168,7 +168,7 @@
         return false;
       }
       escaped = string.replace(STRING_NEWLINES, " \\\n");
-      this.token('STRING', escaped);
+      this.interpolate_string(escaped);
       this.line += count(string, "\n");
       this.i += string.length;
       return true;
@@ -397,6 +397,57 @@
     Lexer.prototype.assignment_error = function assignment_error() {
       throw new Error('SyntaxError: Reserved word "' + this.value() + '" on line ' + this.line + ' can\'t be assigned');
     };
+    // Replace variables and block calls inside double-quoted strings.
+    Lexer.prototype.interpolate_string = function interpolate_string(escaped) {
+      var _a, _b, _c, _d, _e, _f, _g, _h, before, each, group, i, identifier, identifier_match, quote, tokens;
+      if (escaped.length < 3 || escaped.indexOf('"') !== 0) {
+        return this.token('STRING', escaped);
+      } else {
+        tokens = [];
+        quote = escaped.substring(0, 1);
+        escaped = escaped.substring(1, escaped.length - 1);
+        while (escaped.length) {
+          identifier_match = escaped.match(/(^|[\s\S]*?(?:[\\]|\\\\)?)(\$([a-zA-Z_]\w*))/);
+          if (identifier_match) {
+            _a = identifier_match;
+            group = _a[0];
+            before = _a[1];
+            identifier = _a[2];
+            if (before.substring(before.length - 1) === '\\') {
+              if (before.length) {
+                tokens.push(['STRING', quote + before.substring(0, before.length - 1) + identifier + quote]);
+              }
+            } else {
+              if (before.length) {
+                tokens.push(['STRING', quote + before + quote]);
+              }
+              tokens.push(['IDENTIFIER', identifier.substring(1)]);
+            }
+            escaped = escaped.substring(group.length);
+          } else {
+            tokens.push(['STRING', quote + escaped + quote]);
+            escaped = '';
+          }
+        }
+        if (tokens.length > 1) {
+          _d = tokens.length - 1; _e = 1;
+          for (_c = 0, i = _d; (_d <= _e ? i <= _e : i >= _e); (_d <= _e ? i += 1 : i -= 1), _c++) {
+            tokens[i][0] === 'STRING' && tokens[i - 1][0] === 'STRING' ? tokens.splice(i - 1, 2, ['STRING', quote + tokens[i - 1][1].substring(1, tokens[i - 1][1].length - 1) + tokens[i][1].substring(1, tokens[i][1].length - 1) + quote]) : null;
+          }
+        }
+        _f = []; _g = tokens;
+        for (i = 0, _h = _g.length; i < _h; i++) {
+          each = _g[i];
+          _f.push((function() {
+            this.token(each[0], each[1]);
+            if (i < tokens.length - 1) {
+              return this.token('+', '+');
+            }
+          }).call(this));
+        }
+        return _f;
+      }
+    };
     // Helpers
     // -------
     // Add a token to the results, taking note of the line number.

src/lexer.coffee

@@ -166,7 +166,7 @@ exports.Lexer: class Lexer
   string_token: ->
     return false unless string: @match STRING, 1
     escaped: string.replace STRING_NEWLINES, " \\\n"
-    @token 'STRING', escaped
+    @interpolate_string escaped
     @line += count string, "\n"
     @i += string.length
     true
@@ -340,6 +340,36 @@ exports.Lexer: class Lexer
   assignment_error: ->
     throw new Error 'SyntaxError: Reserved word "' + @value() + '" on line ' + @line + ' can\'t be assigned'
 
+  # Replace variables and block calls inside double-quoted strings.
+  interpolate_string: (escaped) ->
+    if escaped.length < 3 or escaped.indexOf('"') isnt 0
+      @token 'STRING', escaped
+    else
+      tokens: []
+      quote: escaped.substring(0, 1)
+      escaped: escaped.substring(1, escaped.length - 1)
+      while escaped.length
+        identifier_match: escaped.match /(^|[\s\S]*?(?:[\\]|\\\\)?)(\$([a-zA-Z_]\w*))/
+        if identifier_match
+          [group, before, identifier]: identifier_match
+          if before.substring(before.length - 1) is '\\'
+            tokens.push ['STRING', quote + before.substring(0, before.length - 1) + identifier + quote] if before.length
+          else
+            tokens.push ['STRING', quote + before + quote] if before.length
+            tokens.push ['IDENTIFIER', identifier.substring(1)]
+          escaped: escaped.substring(group.length)
+        else
+          tokens.push ['STRING', quote + escaped + quote]
+          escaped: ''
+      if tokens.length > 1
+        for i in [tokens.length - 1..1]
+          if tokens[i][0] is 'STRING' and tokens[i - 1][0] is 'STRING'
+            tokens.splice i - 1, 2, ['STRING', quote + tokens[i - 1][1].substring(1, tokens[i - 1][1].length - 1) +
+                                                       tokens[i][1].substring(1, tokens[i][1].length - 1) + quote]
+      for each, i in tokens
+        @token each[0], each[1]
+        @token '+', '+' if i < tokens.length - 1
+
   # Helpers
   # -------
 

test/test_string_interpolation.coffee

@@ -0,0 +1,18 @@
+hello: 'Hello'
+world: 'World'
+ok '$hello $world!' is '$hello $world!'
+ok "$hello $world!" is 'Hello World!'
+ok "[$hello$world]" is '[HelloWorld]'
+ok "$hello$$world" is 'Hello$World'
+
+[s, t, r, i, n, g]: ['s', 't', 'r', 'i', 'n', 'g']
+ok "$s$t$r$i$n$g" is 'string'
+ok "\\$s\\$t\\$r\\$i\\$n\\$g" is '$s$t$r$i$n$g'
+ok "\\$string" is '$string'
+
+ok "\\$Escaping first" is '$Escaping first'
+ok "Escaping \\$in middle" is 'Escaping $in middle'
+ok "Escaping \\$last" is 'Escaping $last'
+
+ok "$$" is '$$'
+ok "\\\\$$" is '\\\\$$'