Fix #4248: Unicode code point escapes

src/lexer.coffee

@@ -261,14 +261,14 @@ exports.Lexer = class Lexer
         indent = attempt if indent is null or 0 < attempt.length < indent.length
       indentRegex = /// \n#{indent} ///g if indent
       @mergeInterpolationTokens tokens, {delimiter}, (value, i) =>
-        value = @formatString value
+        value = @formatString value, delimiter: quote
         value = value.replace indentRegex, '\n' if indentRegex
         value = value.replace LEADING_BLANK_LINE,  '' if i is 0
         value = value.replace TRAILING_BLANK_LINE, '' if i is $
         value
     else
       @mergeInterpolationTokens tokens, {delimiter}, (value, i) =>
-        value = @formatString value
+        value = @formatString value, delimiter: quote
         value = value.replace SIMPLE_STRING_OMIT, (match, offset) ->
           if (i is 0 and offset is 0) or
              (i is $ and offset + match.length is value.length)
@@ -318,6 +318,7 @@ exports.Lexer = class Lexer
       when match = REGEX.exec @chunk
         [regex, body, closed] = match
         @validateEscapes body, isRegex: yes, offsetInChunk: 1
+        body = @formatRegex body, delimiter: '/'
         index = regex.length
         [..., prev] = @tokens
         if prev
@@ -632,7 +633,7 @@ exports.Lexer = class Lexer
           tokensToPush = value
         when 'NEOSTRING'
           # Convert 'NEOSTRING' into 'STRING'.
-          converted = fn token[1], i
+          converted = fn.call this, token[1], i
           # Optimize out empty strings. We ensure that the tokens stream always
           # starts with a string token, though, to make sure that the result
           # really is a string.
@@ -762,11 +763,37 @@ exports.Lexer = class Lexer
                '**', 'SHIFT', 'RELATION', 'COMPARE', '&', '^', '|', '&&', '||',
                'BIN?', 'THROW', 'EXTENDS']
 
-  formatString: (str) ->
-    str.replace STRING_OMIT, '$1'
+  formatString: (str, options) ->
+    @replaceUnicodeCodePointEscapes str.replace(STRING_OMIT, '$1'), options
 
   formatHeregex: (str) ->
-    str.replace HEREGEX_OMIT, '$1$2'
+    @formatRegex str.replace(HEREGEX_OMIT, '$1$2'), delimiter: '///'
+
+  formatRegex: (str, options) ->
+    @replaceUnicodeCodePointEscapes str, options
+
+  unicodeCodePointToUnicodeEscapes: (codePoint) ->
+    toUnicodeEscape = (val) ->
+      str = val.toString 16
+      "\\u#{repeat '0', 4 - str.length}#{str}"
+    return toUnicodeEscape(codePoint) if codePoint < 0x10000
+    # surrogate pair
+    high = Math.floor((codePoint - 0x10000) / 0x400) + 0xD800
+    low = (codePoint - 0x10000) % 0x400 + 0xDC00
+    "#{toUnicodeEscape(high)}#{toUnicodeEscape(low)}"
+
+  # Replace \u{...} with \uxxxx[\uxxxx] in strings and regexes
+  replaceUnicodeCodePointEscapes: (str, options) ->
+    str.replace UNICODE_CODE_POINT_ESCAPE, (match, escapedBackslash, codePointHex, offset) =>
+      return escapedBackslash if escapedBackslash
+
+      codePointDecimal = parseInt codePointHex, 16
+      if codePointDecimal > 0x10ffff
+        @error "unicode code point escapes greater than \\u{10ffff} are not allowed",
+          offset: offset + options.delimiter.length
+          length: codePointHex.length + 4
+
+      @unicodeCodePointToUnicodeEscapes codePointDecimal
 
   # Validates escapes in strings and regexes.
   validateEscapes: (str, options = {}) ->
@@ -777,13 +804,13 @@ exports.Lexer = class Lexer
         STRING_INVALID_ESCAPE
     match = invalidEscapeRegex.exec str
     return unless match
-    [[], before, octal, hex, unicode] = match
+    [[], before, octal, hex, unicodeCodePoint, unicode] = match
     message =
       if octal
         "octal escape sequences are not allowed"
       else
         "invalid escape sequence"
-    invalidEscape = "\\#{octal or hex or unicode}"
+    invalidEscape = "\\#{octal or hex or unicodeCodePoint or unicode}"
     @error "#{message} #{invalidEscape}",
       offset: (options.offsetInChunk ? 0) + match.index + before.length
       length: invalidEscape.length
@@ -970,7 +997,7 @@ REGEX = /// ^
 ///
 
 REGEX_FLAGS  = /^\w*/
-VALID_FLAGS  = /^(?!.*(.).*\1)[imgy]*$/
+VALID_FLAGS  = /^(?!.*(.).*\1)[imguy]*$/
 
 HEREGEX      = /// ^(?: [^\\/#] | \\[\s\S] | /(?!//) | \#(?!\{) )* ///
 
@@ -994,18 +1021,26 @@ STRING_INVALID_ESCAPE = ///
   \\ (
      ?: (0[0-7]|[1-7])             # octal escape
       | (x(?![\da-fA-F]{2}).{0,2}) # hex escape
-      | (u(?![\da-fA-F]{4}).{0,4}) # unicode escape
+      | (u\{(?![\da-fA-F]{1,}\})[^}]*\}?) # unicode code point escape
+      | (u(?!\{|[\da-fA-F]{4}).{0,4}) # unicode escape
   )
 ///
 REGEX_INVALID_ESCAPE = ///
   ( (?:^|[^\\]) (?:\\\\)* )        # make sure the escape isn’t escaped
   \\ (
      ?: (0[0-7])                   # octal escape
       | (x(?![\da-fA-F]{2}).{0,2}) # hex escape
-      | (u(?![\da-fA-F]{4}).{0,4}) # unicode escape
+      | (u\{(?![\da-fA-F]{1,}\})[^}]*\}?) # unicode code point escape
+      | (u(?!\{|[\da-fA-F]{4}).{0,4}) # unicode escape
   )
 ///
 
+UNICODE_CODE_POINT_ESCAPE = ///
+  ( \\\\ )        # make sure the escape isn’t escaped
+  |
+  \\u\{ ( [\da-fA-F]+ ) \}
+///g
+
 LEADING_BLANK_LINE  = /^[^\n\S]*\n/
 TRAILING_BLANK_LINE = /\n[^\n\S]*$/
 

test/error_messages.coffee

@@ -1257,3 +1257,65 @@ test "can't use pattern matches for loop indices", ->
     a for b, {c} in d
              ^^^
   '''
+
+test "#4248: Unicode code point escapes", ->
+  assertErrorFormat '''
+    "a
+      #{b} \\u{G02}
+     c"
+  ''', '''
+    [stdin]:2:8: error: invalid escape sequence \\u{G02}
+      #{b} \\u{G02}
+           ^\^^^^^^
+  '''
+  assertErrorFormat '''
+    /a\\u{}b/
+  ''', '''
+    [stdin]:1:3: error: invalid escape sequence \\u{}
+    /a\\u{}b/
+      ^\^^^
+  '''
+  assertErrorFormat '''
+    ///a \\u{01abc///
+  ''', '''
+    [stdin]:1:6: error: invalid escape sequence \\u{01abc
+    ///a \\u{01abc///
+         ^\^^^^^^^
+  '''
+
+  assertErrorFormat '''
+    /\\u{123} \\u{110000}/
+  ''', '''
+    [stdin]:1:10: error: unicode code point escapes greater than \\u{10ffff} are not allowed
+    /\\u{123} \\u{110000}/
+      \       ^\^^^^^^^^^
+  '''
+
+  assertErrorFormat '''
+    ///abc\\\\\\u{123456}///u
+  ''', '''
+    [stdin]:1:9: error: unicode code point escapes greater than \\u{10ffff} are not allowed
+    ///abc\\\\\\u{123456}///u
+           \ \^\^^^^^^^^^
+  '''
+
+  assertErrorFormat '''
+    """
+      \\u{123}
+      a
+        \\u{00110000}
+      #{ 'b' }
+    """
+  ''', '''
+    [stdin]:4:5: error: unicode code point escapes greater than \\u{10ffff} are not allowed
+        \\u{00110000}
+        ^\^^^^^^^^^^^
+  '''
+
+  assertErrorFormat '''
+    '\\u{a}\\u{1111110000}'
+  ''', '''
+    [stdin]:1:7: error: unicode code point escapes greater than \\u{10ffff} are not allowed
+    '\\u{a}\\u{1111110000}'
+      \    ^\^^^^^^^^^^^^^
+  '''

test/regexps.coffee

@@ -6,6 +6,12 @@
 # * Regexen
 # * Heregexen
 
+# Helper function
+toJS = (str) ->
+  CoffeeScript.compile str, bare: yes
+  .replace /^\s+|\s+$/g, '' # Trim leading/trailing whitespace
+
+
 test "basic regular expression literals", ->
   ok 'a'.match(/a/)
   ok 'a'.match /a/
@@ -286,3 +292,32 @@ test "#3795: Escape otherwise invalid characters", ->
   ok ///#{a}\
///.test 'a\u2029'
   ok ///#{a}\0
       1///.test 'a\x001'
+
+test "#4248: Unicode code point escapes", ->
+  ok /a\u{1ab}c/u.test 'a\u01abc'
+  ok ///#{ 'a' }\u{000001ab}c///u.test 'a\u{1ab}c'
+  ok ///a\u{000001ab}c///u.test 'a\u{1ab}c'
+  ok /a\u{12345}c/u.test 'a\ud808\udf45c'
+
+  # and now without u flag
+  ok /a\u{1ab}c/.test 'a\u01abc'
+  ok ///#{ 'a' }\u{000001ab}c///.test 'a\u{1ab}c'
+  ok ///a\u{000001ab}c///.test 'a\u{1ab}c'
+  ok /a\u{12345}c/.test 'a\ud808\udf45c'
+
+  # rewrite code point escapes
+  input = """
+    /\\u{bcdef}\\u{abc}/u
+    """
+  output = """
+    /\\udab3\\uddef\\u0abc/u;
+  """
+  eq toJS(input), output
+
+  input = """
+    ///#{ 'a' }\\u{bcdef}///
+    """
+  output = """
+    /a\\udab3\\uddef/;
+  """
+  eq toJS(input), output