Fasta builders.

pkg/fasta/lib/src/quote.dart

+// Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+library fasta.quote;
+
+import 'errors.dart' show
+    inputError,
+    internalError;
+
+import 'package:dart_scanner/src/characters.dart' show
+    $BACKSLASH,
+    $BS,
+    $CLOSE_CURLY_BRACKET,
+    $CR,
+    $FF,
+    $LF,
+    $OPEN_CURLY_BRACKET,
+    $SPACE,
+    $TAB,
+    $VTAB,
+    $b,
+    $f,
+    $n,
+    $r,
+    $t,
+    $u,
+    $v,
+    $x,
+    hexDigitValue,
+    isHexDigit;
+
+enum Quote {
+  Single,
+  Double,
+  MultiLineSingle,
+  MultiLineDouble,
+  RawSingle,
+  RawDouble,
+  RawMultiLineSingle,
+  RawMultiLineDouble,
+}
+
+Quote analyzeQuote(String first) {
+  if (first.startsWith('"""')) return Quote.MultiLineDouble;
+  if (first.startsWith('r"""')) return Quote.RawMultiLineDouble;
+  if (first.startsWith("'''")) return Quote.MultiLineSingle;
+  if (first.startsWith("r'''")) return Quote.RawMultiLineSingle;
+  if (first.startsWith('"')) return Quote.Double;
+  if (first.startsWith('r"')) return Quote.RawDouble;
+  if (first.startsWith("'")) return Quote.Single;
+  if (first.startsWith("r'")) return Quote.RawSingle;
+  return internalError("Unexpected string literal: $first");
+}
+
+// Note: based on [StringValidator.quotingFromString]
+// (pkg/compiler/lib/src/string_validator.dart).
+int lengthOfOptionalWhitespacePrefix(String first, int start) {
+  List<int> codeUnits = first.codeUnits;
+  for (int i = start; i < codeUnits.length; i++) {
+    int code = codeUnits[i];
+    if (code == $BACKSLASH) {
+      i++;
+      if (i < codeUnits.length) {
+        code = codeUnits[i];
+      } else {
+        break;
+      }
+    }
+    if (code == $TAB || code == $SPACE) continue;
+    if (code == $CR) {
+      if (i + 1 < codeUnits.length && codeUnits[i] == $LF) {
+        i++;
+      }
+      return i + 1;
+    }
+    if (code == $LF) {
+      return i + 1;
+    }
+    break; // Not a white-space character.
+  }
+  return start;
+}
+
+int firstQuoteLength(String first, Quote quote) {
+  switch (quote) {
+    case Quote.Single:
+    case Quote.Double:
+      return 1;
+
+    case Quote.MultiLineSingle:
+    case Quote.MultiLineDouble:
+      return lengthOfOptionalWhitespacePrefix(first, 3);
+
+    case Quote.RawSingle:
+    case Quote.RawDouble:
+      return 2;
+
+    case Quote.RawMultiLineSingle:
+    case Quote.RawMultiLineDouble:
+      return lengthOfOptionalWhitespacePrefix(first, 4);
+  }
+  return internalError("Unhandled string quote: $quote");
+}
+
+int lastQuoteLength(Quote quote) {
+  switch (quote) {
+    case Quote.Single:
+    case Quote.Double:
+    case Quote.RawSingle:
+    case Quote.RawDouble:
+      return 1;
+
+    case Quote.MultiLineSingle:
+    case Quote.MultiLineDouble:
+    case Quote.RawMultiLineSingle:
+    case Quote.RawMultiLineDouble:
+      return 3;
+  }
+  return internalError("Unhandled string quote: $quote");
+}
+
+String unescapeFirstStringPart(String first, Quote quote) {
+  return unescape(first.substring(firstQuoteLength(first, quote)), quote);
+}
+
+String unescapeLastStringPart(String last, Quote quote) {
+  return unescape(last.substring(0, last.length - lastQuoteLength(quote)),
+      quote);
+}
+
+String unescapeString(String string) {
+  Quote quote = analyzeQuote(string);
+  return unescape(string.substring(
+      firstQuoteLength(string, quote), string.length - lastQuoteLength(quote)),
+      quote);
+}
+
+String unescape(String string, Quote quote) {
+  switch (quote) {
+    case Quote.Single:
+    case Quote.Double:
+    case Quote.MultiLineSingle:
+    case Quote.MultiLineDouble:
+      break;
+
+    case Quote.RawSingle:
+    case Quote.RawDouble:
+    case Quote.RawMultiLineSingle:
+    case Quote.RawMultiLineDouble:
+      return string;
+  }
+  return !string.contains("\\") ? string : unescapeCodeUnits(string.codeUnits);
+}
+
+const String incompleteSequence = "Incomplete escape sequence.";
+
+const String invalidCharacter = "Invalid character in escape sequence.";
+
+const String invalidCodePoint = "Invalid code point.";
+
+// Note: based on
+// [StringValidator.validateString](pkg/compiler/lib/src/string_validator.dart).
+String unescapeCodeUnits(List<int> codeUnits) {
+  // Can't use Uint8List or Uint16List here, the code units may be larger.
+  List<int> result = new List<int>(codeUnits.length);
+  int resultOffset = 0;
+  error(int offset, String message) {
+    inputError(null, null, message);
+  }
+  for (int i = 0; i < codeUnits.length; i++) {
+    int code = codeUnits[i];
+    if (code == $BACKSLASH) {
+      if (codeUnits.length == ++i) return error(i, incompleteSequence);
+      code = codeUnits[i];
+      /// `\n` for newline, equivalent to `\x0A`.
+      /// `\r` for carriage return, equivalent to `\x0D`.
+      /// `\f` for form feed, equivalent to `\x0C`.
+      /// `\b` for backspace, equivalent to `\x08`.
+      /// `\t` for tab, equivalent to `\x09`.
+      /// `\v` for vertical tab, equivalent to `\x0B`.
+      /// `\xXX` for hex escape.
+      /// `\uXXXX` or `\u{XX?X?X?X?X?}` for Unicode hex escape.
+      if (code == $n) {
+        code = $LF;
+      } else if (code == $r) {
+        code = $CR;
+      } else if (code == $f) {
+        code = $FF;
+      } else if (code == $b) {
+        code = $BS;
+      } else if (code == $t) {
+        code = $TAB;
+      } else if (code == $v) {
+        code = $VTAB;
+      } else if (code == $x) {
+        // Expect exactly 2 hex digits.
+        if (codeUnits.length <= i + 2) return error(i, incompleteSequence);
+        code = 0;
+        for (int j = 0; j < 2; j++) {
+          int digit = codeUnits[++i];
+          if (!isHexDigit(digit)) return error(i, invalidCharacter);
+          code = (code << 4) + hexDigitValue(digit);
+        }
+      } else if (code == $u) {
+        if (codeUnits.length == i + 1) return error(i, incompleteSequence);
+        code = codeUnits[i + 1];
+        if (code == $OPEN_CURLY_BRACKET) {
+          // Expect 1-6 hex digits followed by '}'.
+          if (codeUnits.length == ++i) return error(i, incompleteSequence);
+          code = 0;
+          for (int j = 0; j < 7; j++) {
+            if (codeUnits.length == ++i) return error(i, incompleteSequence);
+            int digit = codeUnits[i];
+            if (j != 0 && digit == $CLOSE_CURLY_BRACKET) break;
+            if (!isHexDigit(digit)) return error(i, invalidCharacter);
+            code = (code << 4) + hexDigitValue(digit);
+          }
+        } else {
+          // Expect exactly 4 hex digits.
+          if (codeUnits.length < i + 4) return error(i, incompleteSequence);
+          code = 0;
+          for (int j = 0; j < 4; j++) {
+            int digit = codeUnits[i];
+            if (!isHexDigit(digit)) return error(i, invalidCharacter);
+            code = (code << 4) + hexDigitValue(digit);
+          }
+        }
+      } else {
+        // Nothing, escaped character is passed through;
+      }
+      if (code > 0x10FFFF) return error(i, invalidCodePoint);
+    }
+    result[resultOffset++] = code;
+  }
+  return new String.fromCharCodes(result, 0, resultOffset);
+}