Move package:testing to SDK.

pkg/testing/lib/src/test_dart/status_expression.dart

+// Copyright (c) 2011, 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 status_expression;
+
+/**
+ * Parse and evaluate expressions in a .status file for Dart and V8.
+ * There are set expressions and Boolean expressions in a .status file.
+ * The grammar is:
+ *   BooleanExpression := $variableName == value | $variableName != value |
+ *                        $variableName | (BooleanExpression) |
+ *                        BooleanExpression && BooleanExpression |
+ *                        BooleanExpression || BooleanExpression
+ *
+ *   SetExpression := value | (SetExpression) |
+ *                    SetExpression || SetExpression |
+ *                    SetExpression if BooleanExpression |
+ *                    SetExpression , SetExpression
+ *
+ *  Productions are listed in order of precedence, and the || and , operators
+ *  both evaluate to set union, but with different precedence.
+ *
+ *  Values and variableNames are non-empty strings of word characters, matching
+ *  the RegExp \w+.
+ *
+ *  Expressions evaluate as expected, with values of variables found in
+ *  an environment passed to the evaluator.  The SetExpression "value"
+ *  evaluates to a singleton set containing that value. "A if B" evaluates
+ *  to A if B is true, and to the empty set if B is false.
+ */
+
+class ExprEvaluationException {
+  String error;
+
+  ExprEvaluationException(this.error);
+
+  toString() => error;
+}
+
+class Token {
+  static const String LEFT_PAREN = "(";
+  static const String RIGHT_PAREN = ")";
+  static const String DOLLAR_SYMBOL = r"$";
+  static const String UNION = ",";
+  static const String EQUALS = "==";
+  static const String NOT_EQUALS = "!=";
+  static const String AND = "&&";
+  static const String OR = "||";
+}
+
+class Tokenizer {
+  String expression;
+  List<String> tokens;
+
+  Tokenizer(String this.expression) : tokens = new List<String>();
+
+  // Tokens are : "(", ")", "$", ",", "&&", "||", "==", "!=", and (maximal) \w+.
+  static final testRegexp =
+      new RegExp(r"^([()$\w\s,]|(\&\&)|(\|\|)|(\=\=)|(\!\=))+$");
+  static final regexp = new RegExp(r"[()$,]|(\&\&)|(\|\|)|(\=\=)|(\!\=)|\w+");
+
+  List<String> tokenize() {
+    if (!testRegexp.hasMatch(expression)) {
+      throw new FormatException("Syntax error in '$expression'");
+    }
+    for (Match match in regexp.allMatches(expression)) tokens.add(match[0]);
+    return tokens;
+  }
+}
+
+abstract class BooleanExpression {
+  bool evaluate(Map<String, String> environment);
+}
+
+abstract class SetExpression {
+  Set<String> evaluate(Map<String, String> environment);
+}
+
+class Comparison implements BooleanExpression {
+  TermVariable left;
+  TermConstant right;
+  bool negate;
+
+  Comparison(this.left, this.right, this.negate);
+
+  bool evaluate(environment) {
+    return negate !=
+        (left.termValue(environment) == right.termValue(environment));
+  }
+
+  String toString() =>
+      "(\$${left.name} ${negate ? '!=' : '=='} ${right.value})";
+}
+
+class TermVariable {
+  String name;
+
+  TermVariable(this.name);
+
+  String termValue(environment) {
+    var value = environment[name];
+    if (value == null) {
+      throw new ExprEvaluationException("Could not find '$name' in environment "
+          "while evaluating status file expression.");
+    }
+    return value.toString();
+  }
+}
+
+class TermConstant {
+  String value;
+
+  TermConstant(String this.value);
+
+  String termValue(environment) => value;
+}
+
+class BooleanVariable implements BooleanExpression {
+  TermVariable variable;
+
+  BooleanVariable(this.variable);
+
+  bool evaluate(environment) => variable.termValue(environment) == 'true';
+  String toString() => "(bool \$${variable.name})";
+}
+
+class BooleanOperation implements BooleanExpression {
+  String op;
+  BooleanExpression left;
+  BooleanExpression right;
+
+  BooleanOperation(this.op, this.left, this.right);
+
+  bool evaluate(environment) => (op == Token.AND)
+      ? left.evaluate(environment) && right.evaluate(environment)
+      : left.evaluate(environment) || right.evaluate(environment);
+  String toString() => "($left $op $right)";
+}
+
+class SetUnion implements SetExpression {
+  SetExpression left;
+  SetExpression right;
+
+  SetUnion(this.left, this.right);
+
+  // Overwrites left.evaluate(env).
+  // Set.addAll does not return this.
+  Set<String> evaluate(environment) {
+    Set<String> result = left.evaluate(environment);
+    result.addAll(right.evaluate(environment));
+    return result;
+  }
+
+  String toString() => "($left || $right)";
+}
+
+class SetIf implements SetExpression {
+  SetExpression left;
+  BooleanExpression right;
+
+  SetIf(this.left, this.right);
+
+  Set<String> evaluate(environment) => right.evaluate(environment)
+      ? left.evaluate(environment)
+      : new Set<String>();
+  String toString() => "($left if $right)";
+}
+
+class SetConstant implements SetExpression {
+  String value;
+
+  SetConstant(String v) : value = v.toLowerCase();
+
+  Set<String> evaluate(environment) => new Set<String>.from([value]);
+  String toString() => value;
+}
+
+// An iterator that allows peeking at the current token.
+class Scanner {
+  List<String> tokens;
+  Iterator tokenIterator;
+  String current;
+
+  Scanner(this.tokens) {
+    tokenIterator = tokens.iterator;
+    advance();
+  }
+
+  bool hasMore() => current != null;
+
+  void advance() {
+    current = tokenIterator.moveNext() ? tokenIterator.current : null;
+  }
+}
+
+class ExpressionParser {
+  Scanner scanner;
+
+  ExpressionParser(this.scanner);
+
+  SetExpression parseSetExpression() => parseSetUnion();
+
+  SetExpression parseSetUnion() {
+    SetExpression left = parseSetIf();
+    while (scanner.hasMore() && scanner.current == Token.UNION) {
+      scanner.advance();
+      SetExpression right = parseSetIf();
+      left = new SetUnion(left, right);
+    }
+    return left;
+  }
+
+  SetExpression parseSetIf() {
+    SetExpression left = parseSetOr();
+    while (scanner.hasMore() && scanner.current == "if") {
+      scanner.advance();
+      BooleanExpression right = parseBooleanExpression();
+      left = new SetIf(left, right);
+    }
+    return left;
+  }
+
+  SetExpression parseSetOr() {
+    SetExpression left = parseSetAtomic();
+    while (scanner.hasMore() && scanner.current == Token.OR) {
+      scanner.advance();
+      SetExpression right = parseSetAtomic();
+      left = new SetUnion(left, right);
+    }
+    return left;
+  }
+
+  SetExpression parseSetAtomic() {
+    if (scanner.current == Token.LEFT_PAREN) {
+      scanner.advance();
+      SetExpression value = parseSetExpression();
+      if (scanner.current != Token.RIGHT_PAREN) {
+        throw new FormatException("Missing right parenthesis in expression");
+      }
+      scanner.advance();
+      return value;
+    }
+    if (!new RegExp(r"^\w+$").hasMatch(scanner.current)) {
+      throw new FormatException(
+          "Expected identifier in expression, got ${scanner.current}");
+    }
+    SetExpression value = new SetConstant(scanner.current);
+    scanner.advance();
+    return value;
+  }
+
+  BooleanExpression parseBooleanExpression() => parseBooleanOr();
+
+  BooleanExpression parseBooleanOr() {
+    BooleanExpression left = parseBooleanAnd();
+    while (scanner.hasMore() && scanner.current == Token.OR) {
+      scanner.advance();
+      BooleanExpression right = parseBooleanAnd();
+      left = new BooleanOperation(Token.OR, left, right);
+    }
+    return left;
+  }
+
+  BooleanExpression parseBooleanAnd() {
+    BooleanExpression left = parseBooleanAtomic();
+    while (scanner.hasMore() && scanner.current == Token.AND) {
+      scanner.advance();
+      BooleanExpression right = parseBooleanAtomic();
+      left = new BooleanOperation(Token.AND, left, right);
+    }
+    return left;
+  }
+
+  BooleanExpression parseBooleanAtomic() {
+    if (scanner.current == Token.LEFT_PAREN) {
+      scanner.advance();
+      BooleanExpression value = parseBooleanExpression();
+      if (scanner.current != Token.RIGHT_PAREN) {
+        throw new FormatException("Missing right parenthesis in expression");
+      }
+      scanner.advance();
+      return value;
+    }
+
+    // The only atomic booleans are of the form $variable == value or
+    // of the form $variable.
+    if (scanner.current != Token.DOLLAR_SYMBOL) {
+      throw new FormatException(
+          "Expected \$ in expression, got ${scanner.current}");
+    }
+    scanner.advance();
+    if (!new RegExp(r"^\w+$").hasMatch(scanner.current)) {
+      throw new FormatException(
+          "Expected identifier in expression, got ${scanner.current}");
+    }
+    TermVariable left = new TermVariable(scanner.current);
+    scanner.advance();
+    if (scanner.current == Token.EQUALS ||
+        scanner.current == Token.NOT_EQUALS) {
+      bool negate = scanner.current == Token.NOT_EQUALS;
+      scanner.advance();
+      if (!new RegExp(r"^\w+$").hasMatch(scanner.current)) {
+        throw new FormatException(
+            "Expected value in expression, got ${scanner.current}");
+      }
+      TermConstant right = new TermConstant(scanner.current);
+      scanner.advance();
+      return new Comparison(left, right, negate);
+    } else {
+      return new BooleanVariable(left);
+    }
+  }
+}