Add support for extended Unicode escape sequences in strings and templates

src/compiler/core.ts

@@ -623,29 +623,6 @@ module ts {
         "\u0085": "\\u0085"  // nextLine
     };
 
-    /**
-     * Based heavily on the abstract 'Quote'/ 'QuoteJSONString' operation from ECMA-262 (24.3.2.2),
-     * but augmented for a few select characters.
-     * Note that this doesn't actually wrap the input in double quotes.
-     */
-    export function escapeString(s: string): string {
-        // Prioritize '"' and '\'
-        s = backslashOrDoubleQuote.test(s) ? s.replace(backslashOrDoubleQuote, getReplacement) : s;
-        s = escapedCharsRegExp.test(s) ? s.replace(escapedCharsRegExp, getReplacement) : s;
-
-        return s;
-
-        function getReplacement(c: string) {
-            return escapedCharsMap[c] || unicodeEscape(c);
-        }
-
-        function unicodeEscape(c: string): string {
-            var hexCharCode = c.charCodeAt(0).toString(16);
-            var paddedHexCode = ("0000" + hexCharCode).slice(-4);
-            return "\\u" + paddedHexCode;
-        }
-    }
-
     export function getDefaultLibFileName(options: CompilerOptions): string {
         return options.target === ScriptTarget.ES6 ? "lib.es6.d.ts" : "lib.d.ts";
     }

src/compiler/diagnosticInformationMap.generated.ts

@@ -155,6 +155,8 @@ module ts {
         Catch_clause_variable_name_must_be_an_identifier: { code: 1195, category: DiagnosticCategory.Error, key: "Catch clause variable name must be an identifier." },
         Catch_clause_variable_cannot_have_a_type_annotation: { code: 1196, category: DiagnosticCategory.Error, key: "Catch clause variable cannot have a type annotation." },
         Catch_clause_variable_cannot_have_an_initializer: { code: 1197, category: DiagnosticCategory.Error, key: "Catch clause variable cannot have an initializer." },
+        An_extended_Unicode_escape_value_must_be_between_0x0_and_0x10FFFF_inclusive: { code: 1198, category: DiagnosticCategory.Error, key: "An extended Unicode escape value must be between 0x0 and 0x10FFFF inclusive." },
+        Unterminated_Unicode_escape_sequence: { code: 1199, category: DiagnosticCategory.Error, key: "Unterminated Unicode escape sequence." },
         Duplicate_identifier_0: { code: 2300, category: DiagnosticCategory.Error, key: "Duplicate identifier '{0}'." },
         Initializer_of_instance_member_variable_0_cannot_reference_identifier_1_declared_in_the_constructor: { code: 2301, category: DiagnosticCategory.Error, key: "Initializer of instance member variable '{0}' cannot reference identifier '{1}' declared in the constructor." },
         Static_members_cannot_reference_class_type_parameters: { code: 2302, category: DiagnosticCategory.Error, key: "Static members cannot reference class type parameters." },

src/compiler/diagnosticMessages.json

@@ -611,7 +611,14 @@
         "category": "Error",
         "code": 1197
     },
-
+    "An extended Unicode escape value must be between 0x0 and 0x10FFFF inclusive.": {
+        "category": "Error",
+        "code": 1198
+    },
+    "Unterminated Unicode escape sequence.": {
+        "category": "Error",
+        "code":  1199
+    },
     "Duplicate identifier '{0}'.": {
         "category": "Error",
         "code": 2300

src/compiler/emitter.ts

@@ -2178,36 +2178,70 @@ module ts {
                 }
             }
 
-            function isBinaryOrOctalIntegerLiteral(text: string): boolean {
-                if (text.length <= 0) {
-                    return false;
-                }
-
-                if (text.charCodeAt(1) === CharacterCodes.B || text.charCodeAt(1) === CharacterCodes.b ||
-                    text.charCodeAt(1) === CharacterCodes.O || text.charCodeAt(1) === CharacterCodes.o) {
-                    return true;
+            function isBinaryOrOctalIntegerLiteral(node: LiteralExpression, text: string): boolean {
+                if (node.kind === SyntaxKind.NumericLiteral && text.length > 1) {
+                    switch (text.charCodeAt(1)) {
+                        case CharacterCodes.b:
+                        case CharacterCodes.B:
+                        case CharacterCodes.o:
+                        case CharacterCodes.O:
+                            return true;
+                    }
                 }
+
                 return false;
             }
 
             function emitLiteral(node: LiteralExpression) {
-                var text = languageVersion < ScriptTarget.ES6 && isTemplateLiteralKind(node.kind) ? getTemplateLiteralAsStringLiteral(node) :
-                    node.parent ? getSourceTextOfNodeFromSourceFile(currentSourceFile, node) :
-                        node.text;
+                var text = getLiteralText(node);
+
                 if (compilerOptions.sourceMap && (node.kind === SyntaxKind.StringLiteral || isTemplateLiteralKind(node.kind))) {
                     writer.writeLiteral(text);
                 }
-                // For version below ES6, emit binary integer literal and octal integer literal in canonical form
-                else if (languageVersion < ScriptTarget.ES6 && node.kind === SyntaxKind.NumericLiteral && isBinaryOrOctalIntegerLiteral(text)) {
+                // For versions below ES6, emit binary & octal literals in their canonical decimal form.
+                else if (languageVersion < ScriptTarget.ES6 && isBinaryOrOctalIntegerLiteral(node, text)) {
                     write(node.text);
                 }
                 else {
                     write(text);
                 }
             }
-
-            function getTemplateLiteralAsStringLiteral(node: LiteralExpression): string {
-                return '"' + escapeString(node.text) + '"';
+
+            function getLiteralText(node: LiteralExpression) {
+                // Any template literal or string literal with an extended escape
+                // (e.g. "\u{0067}") will need to be downleveled as a escaped string literal.
+                if (languageVersion < ScriptTarget.ES6 && (isTemplateLiteralKind(node.kind) || node.hasExtendedUnicodeEscape)) {
+                    return getQuotedEscapedLiteralText('"', node.text, '"');
+                }
+
+                // If we don't need to downlevel and we can reach the original source text using
+                // the node's parent reference, then simply get the text as it was originally written.
+                if (node.parent) {
+                    return getSourceTextOfNodeFromSourceFile(currentSourceFile, node);
+                }
+
+                // If we can't reach the original source text, use the canonical form if it's a number,
+                // or an escaped quoted form of the original text if it's string-like.
+                switch (node.kind) {
+                    case SyntaxKind.StringLiteral:
+                        return getQuotedEscapedLiteralText('"', node.text, '"');
+                    case SyntaxKind.NoSubstitutionTemplateLiteral:
+                        return getQuotedEscapedLiteralText('`', node.text, '`');
+                    case SyntaxKind.TemplateHead:
+                        return getQuotedEscapedLiteralText('`', node.text, '${');
+                    case SyntaxKind.TemplateMiddle:
+                        return getQuotedEscapedLiteralText('}', node.text, '${');
+                    case SyntaxKind.TemplateTail:
+                        return getQuotedEscapedLiteralText('}', node.text, '`');
+                    case SyntaxKind.NumericLiteral:
+                        return node.text;
+                }
+
+                Debug.fail(`Literal kind '${node.kind}' not accounted for.`);
+            }
+
+            function getQuotedEscapedLiteralText(leftQuote: string, text: string, rightQuote: string) {
+                return leftQuote + escapeNonAsciiCharacters(escapeString(text)) + rightQuote;
             }
 
             function emitDownlevelRawTemplateLiteral(node: LiteralExpression) {

src/compiler/parser.ts

@@ -2163,6 +2163,10 @@ module ts {
             var text = scanner.getTokenValue();
             node.text = internName ? internIdentifier(text) : text;
 
+            if (scanner.hasExtendedUnicodeEscape()) {
+                node.hasExtendedUnicodeEscape = true;
+            }
+
             if (scanner.isUnterminated()) {
                 node.isUnterminated = true;
             }

src/compiler/scanner.ts

@@ -14,6 +14,7 @@ module ts {
         getTokenPos(): number;
         getTokenText(): string;
         getTokenValue(): string;
+        hasExtendedUnicodeEscape(): boolean;
         hasPrecedingLineBreak(): boolean;
         isIdentifier(): boolean;
         isReservedWord(): boolean;
@@ -556,6 +557,7 @@ module ts {
         var token: SyntaxKind;
         var tokenValue: string;
         var precedingLineBreak: boolean;
+        var hasExtendedUnicodeEscape: boolean;
         var tokenIsUnterminated: boolean;
 
         function error(message: DiagnosticMessage, length?: number): void {
@@ -606,11 +608,27 @@ module ts {
             }
             return +(text.substring(start, pos));
         }
+
+        /**
+         * Scans the given number of hexadecimal digits in the text,
+         * returning -1 if the given number is unavailable.
+         */
+        function scanExactNumberOfHexDigits(count: number): number {
+            return scanHexDigits(/*minCount*/ count, /*scanAsManyAsPossible*/ false);
+        }
+
+        /**
+         * Scans as many hexadecimal digits as are available in the text,
+         * returning -1 if the given number of digits was unavailable.
+         */
+        function scanMinimumNumberOfHexDigits(count: number): number {
+            return scanHexDigits(/*minCount*/ count, /*scanAsManyAsPossible*/ true);
+        }
 
-        function scanHexDigits(count: number, mustMatchCount?: boolean): number {
+        function scanHexDigits(minCount: number, scanAsManyAsPossible: boolean): number {
             var digits = 0;
             var value = 0;
-            while (digits < count || !mustMatchCount) {
+            while (digits < minCount || scanAsManyAsPossible) {
                 var ch = text.charCodeAt(pos);
                 if (ch >= CharacterCodes._0 && ch <= CharacterCodes._9) {
                     value = value * 16 + ch - CharacterCodes._0;
@@ -627,7 +645,7 @@ module ts {
                 pos++;
                 digits++;
             }
-            if (digits < count) {
+            if (digits < minCount) {
                 value = -1;
             }
             return value;
@@ -764,16 +782,20 @@ module ts {
                     return "\'";
                 case CharacterCodes.doubleQuote:
                     return "\"";
-                case CharacterCodes.x:
                 case CharacterCodes.u:
-                    var ch = scanHexDigits(ch === CharacterCodes.x ? 2 : 4, /*mustMatchCount*/ true);
-                    if (ch >= 0) {
-                        return String.fromCharCode(ch);
-                    }
-                    else {
-                        error(Diagnostics.Hexadecimal_digit_expected);
-                        return ""
+                    // '\u{DDDDDDDD}'
+                    if (pos < len && text.charCodeAt(pos) === CharacterCodes.openBrace) {
+                        hasExtendedUnicodeEscape = true;
+                        pos++;
+                        return scanExtendedUnicodeEscape();
                     }
+
+                    // '\uDDDD'
+                    return scanHexadecimalEscape(/*numDigits*/ 4)
+
+                case CharacterCodes.x:
+                    // '\xDD'
+                    return scanHexadecimalEscape(/*numDigits*/ 2)
 
                 // when encountering a LineContinuation (i.e. a backslash and a line terminator sequence),
                 // the line terminator is interpreted to be "the empty code unit sequence".
@@ -790,14 +812,74 @@ module ts {
                     return String.fromCharCode(ch);
             }
         }
+
+        function scanHexadecimalEscape(numDigits: number): string {
+            var escapedValue = scanExactNumberOfHexDigits(numDigits);
+
+            if (escapedValue >= 0) {
+                return String.fromCharCode(escapedValue);
+            }
+            else {
+                error(Diagnostics.Hexadecimal_digit_expected);
+                return ""
+            }
+        }
+
+        function scanExtendedUnicodeEscape(): string {
+            var escapedValue = scanMinimumNumberOfHexDigits(1);
+            var isInvalidExtendedEscape = false;
+
+            // Validate the value of the digit
+            if (escapedValue < 0) {
+                error(Diagnostics.Hexadecimal_digit_expected)
+                isInvalidExtendedEscape = true;
+            }
+            else if (escapedValue > 0x10FFFF) {
+                error(Diagnostics.An_extended_Unicode_escape_value_must_be_between_0x0_and_0x10FFFF_inclusive);
+                isInvalidExtendedEscape = true;
+            }
+
+            if (pos >= len) {
+                error(Diagnostics.Unexpected_end_of_text);
+                isInvalidExtendedEscape = true;
+            }
+            else if (text.charCodeAt(pos) == CharacterCodes.closeBrace) {
+                // Only swallow the following character up if it's a '}'.
+                pos++;
+            }
+            else {
+                error(Diagnostics.Unterminated_Unicode_escape_sequence);
+                isInvalidExtendedEscape = true;
+            }
+
+            if (isInvalidExtendedEscape) {
+                return "";
+            }
+
+            return utf16EncodeAsString(escapedValue);
+        }
+
+        // Derived from the 10.1.1 UTF16Encoding of the ES6 Spec.
+        function utf16EncodeAsString(codePoint: number): string {
+            Debug.assert(0x0 <= codePoint && codePoint <= 0x10FFFF);
+
+            if (codePoint <= 65535) {
+                return String.fromCharCode(codePoint);
+            }
+
+            var codeUnit1 = Math.floor((codePoint - 65536) / 1024) + 0xD800;
+            var codeUnit2 = ((codePoint - 65536) % 1024) + 0xDC00;
+
+            return String.fromCharCode(codeUnit1, codeUnit2);
+        }
 
         // Current character is known to be a backslash. Check for Unicode escape of the form '\uXXXX'
         // and return code point value if valid Unicode escape is found. Otherwise return -1.
         function peekUnicodeEscape(): number {
             if (pos + 5 < len && text.charCodeAt(pos + 1) === CharacterCodes.u) {
                 var start = pos;
                 pos += 2;
-                var value = scanHexDigits(4, /*mustMatchCount*/ true);
+                var value = scanExactNumberOfHexDigits(4);
                 pos = start;
                 return value;
             }
@@ -869,6 +951,7 @@ module ts {
 
         function scan(): SyntaxKind {
             startPos = pos;
+            hasExtendedUnicodeEscape = false;
             precedingLineBreak = false;
             tokenIsUnterminated = false;
             while (true) {
@@ -1034,7 +1117,7 @@ module ts {
                     case CharacterCodes._0:
                         if (pos + 2 < len && (text.charCodeAt(pos + 1) === CharacterCodes.X || text.charCodeAt(pos + 1) === CharacterCodes.x)) {
                             pos += 2;
-                            var value = scanHexDigits(1, /*mustMatchCount*/ false);
+                            var value = scanMinimumNumberOfHexDigits(1);
                             if (value < 0) {
                                 error(Diagnostics.Hexadecimal_digit_expected);
                                 value = 0;
@@ -1336,6 +1419,7 @@ module ts {
             getTokenPos: () => tokenPos,
             getTokenText: () => text.substring(tokenPos, pos),
             getTokenValue: () => tokenValue,
+            hasExtendedUnicodeEscape: () => hasExtendedUnicodeEscape,
             hasPrecedingLineBreak: () => precedingLineBreak,
             isIdentifier: () => token === SyntaxKind.Identifier || token > SyntaxKind.LastReservedWord,
             isReservedWord: () => token >= SyntaxKind.FirstReservedWord && token <= SyntaxKind.LastReservedWord,

src/compiler/types.ts

@@ -655,6 +655,7 @@ module ts {
     export interface LiteralExpression extends PrimaryExpression {
         text: string;
         isUnterminated?: boolean;
+        hasExtendedUnicodeEscape?: boolean;
     }
 
     export interface StringLiteralExpression extends LiteralExpression {