ExpressionType TranslateExpression(IfExpression e)
{
Types.Type temp;
ExpressionType test = TranslateExpression(e.Test);
ExpressionType then = TranslateExpression(e.Then);
ExpressionType els = e.Else == null ? null : TranslateExpression(e.Else);
CheckInteger(e.Test.Pos, test);
if (els != null)
{
if ((temp = CheckIfType(e.Pos, then, els)) != null)
{
return(new ExpressionType(Translate.TranslateIfThenElseExp(test.Exp, then.Exp, els.Exp), temp));
}
else
{
Error.Report(e.Pos, "Type mismatch in if expression");
return(new ExpressionType(null, Types.Type._void));
}
}
else
{
if (then.Type.CoerceTo(Types.Type._void))
{
return(new ExpressionType(Translate.TranslateIfThenElseExp(test.Exp, then.Exp, null), Types.Type._void));
}
else
{
Error.Report(e.Pos, "Then clause must return 'void'");
return(new ExpressionType(null, Types.Type._void));
}
}
}
private void CompileIfExpression(InstructionSet instructionSet, IfExpression exp, Scope scope, LocalTable table)
{
CompileExpression(instructionSet, exp.Condition, scope, table);
var anchor1 = new Anchor();
instructionSet.Define(InstructionType.BranchUnless, anchor1);
CompileBlockStatement(instructionSet, exp.Consequence, scope, table);
anchor1.Line = instructionSet.Count + 1;
if (exp.Alternative == null)
{
anchor1.Line--;
instructionSet.Define(InstructionType.PutNull);
return;
}
var anchor2 = new Anchor();
instructionSet.Define(InstructionType.Jump, anchor2);
CompileBlockStatement(instructionSet, exp.Alternative, scope, table);
anchor2.Line = instructionSet.Count;
}
public int Visit(IfExpression expression)
{
for (var i = 0; i < expression.Branches.Count; i++)
{
var branch = expression.Branches[i];
_writer.Write(i == 0 ? "if" : "else if");
_writer.Write(" (");
branch.Condition.Accept(this);
_writer.WriteLine(")");
branch.Block.Accept(this);
if (expression.Else != null || i < expression.Branches.Count - 1)
{
_writer.WriteLine();
}
}
if (expression.Else != null)
{
_writer.WriteLine("else ");
expression.Else.Block.Accept(this);
}
return(0);
}
public void GetAndEvaluateIfExpression()
{
IfExpression expression = IfExpression.Instance;
Assert.IsNotNull(expression);
Machine machine = new Machine();
machine.Push(true);
machine.Push(new IntegerExpression(1));
machine.Push(new IntegerExpression(2));
expression.Evaluate(machine);
Assert.AreEqual(1, machine.StackCount);
Assert.AreEqual(1, machine.Pop());
machine.Push(false);
machine.Push(new IntegerExpression(1));
machine.Push(new IntegerExpression(2));
expression.Evaluate(machine);
Assert.AreEqual(1, machine.StackCount);
Assert.AreEqual(2, machine.Pop());
}
protected virtual Expression VisitIf(IfExpression node)
{
Visit(node.Test);
Visit(node.IfTrue);
Visit(node.IfFalse);
return(node);
}
public void EvaluateElseExpression()
{
IfExpression ifexpr = new IfExpression(new ConstantExpression(false), new ConstantExpression(1), new ConstantExpression(2));
Assert.AreSame(TypeInfo.Int, ifexpr.TypeInfo);
Assert.AreEqual(2, ifexpr.Evaluate(null));
}
private Expression ParseIfExpression()
{
var expression = new IfExpression();
expression.Token = this._curToken;
if (!this.ExpectPeek(TokenType.LPAREN))
{
throw new ParserException($"Expect peek a {TokenType.LPAREN} but got {this._peekToken}");
}
this.NextToken();
expression.Condition = this.ParseExpression(Precedence.LOWEST);
if (!this.ExpectPeek(TokenType.RPAREN))
{
throw new ParserException($"Expect peek a {TokenType.RPAREN}, but got {this._peekToken}");
}
if (!this.ExpectPeek(TokenType.LBRACE))
{
throw new ParserException($"Expect peek a {TokenType.LBRACE}, but got {this._peekToken}");
}
expression.Consequence = this.ParseBlockStatement();
if (this.PeekTokenIs(TokenType.ELSE))
{
this.NextToken();
if (!this.ExpectPeek(TokenType.LBRACE))
{
throw new ParserException($"Expect peek a {TokenType.LBRACE}, but got {this._peekToken}");
}
expression.Alternative = this.ParseBlockStatement();
}
return(expression);
}
public void Parser_CanParseIfElseExpressions()
{
string input = @"
if (x < y) { x } else { y }
";
AST result = this.subject.ParseProgram(input);
Assert.Equal(1, result.Program.Statements.Count);
Assert.Empty(result.Errors);
ExpressionStatement actual = this.AssertAndCast <ExpressionStatement>(result.Program.Statements[0]);
IfExpression ifExpression = this.AssertAndCast <IfExpression>(actual.Expression);
Assert.Equal("(x < y)", ifExpression.Condition.StringValue);
Assert.Equal(1, ifExpression.Consequence.Statements.Count);
ExpressionStatement expr = this.AssertAndCast <ExpressionStatement>(ifExpression.Consequence.Statements[0]);
Identifier identifier = this.AssertAndCast <Identifier>(expr.Expression);
Assert.Equal("x", identifier.Value);
Assert.NotNull(ifExpression.Alternative);
Assert.Equal(1, ifExpression.Alternative.Statements.Count);
expr = this.AssertAndCast <ExpressionStatement>(ifExpression.Alternative.Statements[0]);
identifier = this.AssertAndCast <Identifier>(expr.Expression);
Assert.Equal("y", identifier.Value);
}
public IExpression Parse(Parser parser, Token token)
{
if (!parser.LookAhead().IsType(TokenType.Identifier))
{
throw new ParseException(token.Position, "Tag name must be a valid identifier.");
}
IExpression nameEx = parser.ParseExpression <TagExpression>();
string name = ((IdentifierExpression)nameEx).Name;
var parameters = new List <IExpression>();
while (parser.LookAhead().IsType(TokenType.Identifier))
{
IExpression param = parser.ParseExpression <TagExpression>();
parameters.Add(param);
}
parser.Match(TokenType.RightBracket); // optional
if (new[] { "if", "elsif", "else" }.Contains(name))
{
var children = new List <IExpression>();
IfExpression fallback = null;
TagExpression childTag;
do
{
IExpression child = parser.ParseExpression <IfExpression>();
childTag = child as TagExpression;
var ifChild = childTag as IfExpression;
if (childTag == null || childTag.Name != "endif" && (ifChild == null || ifChild.IsRoot))
{
children.Add(child);
}
else
{
fallback = ifChild;
}
} while (fallback == null && childTag?.Name != "endif");
return(new IfExpression(name, parameters, children, fallback));
}
if (name == "macro")
{
var children = new List <IExpression>();
TagExpression childTag;
do
{
IExpression child = parser.ParseExpression <IfExpression>();
childTag = child as TagExpression;
if (childTag == null || childTag.Name != "endmacro")
{
children.Add(child);
}
} while (childTag?.Name != "endmacro");
return(new MacroExpression(name, parameters, children));
}
return(new TagExpression(name, parameters));
}
public void ExecuteThenWhenConditionIsZero()
{
IfExpression cmd = new IfExpression(new ConstantExpression(0), new AssignExpression("one", new ConstantExpression(1)));
Context context = new Context();
Assert.AreEqual(1, cmd.Evaluate(context));
Assert.AreEqual(1, context.GetValue("one"));
}
public void DontExecuteThenWhenConditionIsNull()
{
IfExpression cmd = new IfExpression(new ConstantExpression(null), new AssignExpression("one", new ConstantExpression(1)));
Context context = new Context();
Assert.IsNull(cmd.Evaluate(context));
Assert.IsNull(context.GetValue("one"));
}
public void ExecuteElseWhenConditionIsNull()
{
IfExpression cmd = new IfExpression(new ConstantExpression(null), new AssignExpression("one", new ConstantExpression(1)), new AssignExpression("two", new ConstantExpression(2)));
Context context = new Context();
Assert.AreEqual(cmd.Evaluate(context), 2);
Assert.IsNull(context.GetValue("one"));
Assert.AreEqual(2, context.GetValue("two"));
}
public void TestAppendString()
{
var expr = new IfExpression(new IntegerConstantExpression(1));
var builder = new StringBuilder();
expr.AppendString(builder);
Assert.That(builder.ToString(), Is.EqualTo("if (1) { ... }"));
// NOTE: does not output Expressions block
}
private IfExpression Parse(string input)
{
var tokenizer = new PositionalTokenizer(Tokenizer.CreateTokenizer(input));
tokenizer.Match("if");
var expr = IfExpression.Parse(tokenizer);
Assert.That(expr, Is.InstanceOf <IfExpression>());
return((IfExpression)expr);
}
public void ParseIfCommandWithCompositeThenCommand()
{
Parser parser = new Parser("if 1\n a=1\n b=2\nend");
var expected = new IfExpression(new ConstantExpression(1), new CompositeExpression(new IExpression[] { new AssignExpression("a", new ConstantExpression(1)), new AssignExpression("b", new ConstantExpression(2)) }));
var result = parser.ParseCommand();
Assert.IsNotNull(result);
Assert.AreEqual(expected, result);
Assert.IsNull(parser.ParseCommand());
}
public void ParseSimpleIfCommandWithSemicolonOneLine()
{
Parser parser = new Parser("if 1; a=1 end");
var expected = new IfExpression(new ConstantExpression(1), new AssignExpression("a", new ConstantExpression(1)));
var result = parser.ParseCommand();
Assert.IsNotNull(result);
Assert.AreEqual(expected, result);
Assert.IsNull(parser.ParseCommand());
}
public void ParseSimpleIfElseCommand()
{
Parser parser = new Parser("if 1\n a=1\nelse\n a=2\nend");
var expected = new IfExpression(new ConstantExpression(1), new AssignExpression("a", new ConstantExpression(1)), new AssignExpression("a", new ConstantExpression(2)));
var result = parser.ParseCommand();
Assert.IsNotNull(result);
Assert.AreEqual(expected, result);
Assert.IsNull(parser.ParseCommand());
}
private IfInstruction PopulateIfCondition(ScopePrototype scope, IfExpression ifExpression, ElseExpression elseExpression)
{
var ifInstruction = new IfInstruction(scope, ifExpression);
PopulateInstructions(ifExpression.Instructions, ifInstruction.IfBlock, scope);
if (elseExpression != null)
{
PopulateInstructions(elseExpression.Instructions, ifInstruction.ElseBlock, scope);
}
return(ifInstruction);
}
void PrintExpression(IfExpression e, int d)
{
SayLn("IfExpression(");
PrintExpression(e.Test, d + 1); SayLn(",");
PrintExpression(e.Then, d + 1);
if (e.Else != null)
{ /* else is optional */
SayLn(",");
PrintExpression(e.Else, d + 1);
}
Say(")");
}
private AphidObject InterpretIfExpression(IfExpression expression)
{
if ((bool)ValueHelper.Unwrap(InterpretExpression(expression.Condition)))
{
InterpretChild(expression.Body);
}
else if (expression.ElseBody != null)
{
InterpretChild(expression.ElseBody);
}
return(null);
}
public TypeDenoter VisitIfExpression(IfExpression ast, Void arg)
{
var e1Type = ast.TestExpression.Visit(this);
CheckAndReportError(e1Type == StandardEnvironment.BooleanType,
"Boolean expression expected here", ast.TestExpression);
var e2Type = ast.TrueExpression.Visit(this);
var e3Type = ast.FalseExpression.Visit(this);
CheckAndReportError(e2Type.Equals(e3Type), "incompatible limbs in if-expression", ast);
return(ast.Type = e2Type);
}
private bool EvaluateIf(IfExpression ifExpression, InterpreterScope scope)
{
ParseErrorExpression error;
bool result = ifExpression.Condition.IsTrue(scope, out error);
if (error != null)
{
Error = error;
return(false);
}
return(Evaluate(result ? ifExpression.Expressions : ifExpression.ElseExpressions, scope));
}
public int VisitIfExpression(IfExpression ast, Frame frame)
{
ast.Type.Visit(this, null);
ast.TestExpression.Visit(this, frame);
var jumpifAddr = _emitter.Emit(OpCode.JUMPIF, Machine.FalseValue, Register.CB);
var valSize = ast.TrueExpression.Visit(this, frame);
var jumpAddr = _emitter.Emit(OpCode.JUMP, Register.CB);
_emitter.Patch(jumpifAddr);
ast.FalseExpression.Visit(this, frame);
_emitter.Patch(jumpAddr);
return(valSize);
}
private CodeStatementCollection GenerateImperativeStatement(IfExpression node)
{
var condition = GenerateImperativeExpression(node.Condition, isCondition: true);
var trueStmts = GenerateImperativeStatements(node.Body).OfType <CodeStatement>().ToArray();
var falseStmts = node.ElseBody != null?
GenerateImperativeStatements(node.ElseBody).OfType <CodeStatement>().ToArray() :
Array.Empty <CodeStatement>();
var stmt = new CodeConditionStatement(condition, trueStmts, falseStmts);
return(new CodeStatementCollection(new[] { stmt }));
}
protected override List <AphidExpression> MutateCore(AphidExpression expression, out bool hasChanged)
{
if (expression.Type != AphidExpressionType.SwitchExpression)
{
hasChanged = false;
return(null);
}
hasChanged = true;
var switchExp = expression.ToSwitch();
var id = NextId();
var idDecl = new BinaryOperatorExpression(
id,
AphidTokenType.AssignmentOperator,
switchExp.Expression);
var cases = switchExp.Cases
.Select(x => new
{
Case = x,
Condition = CreateCaseCondition(x, id),
});
IfExpression rootIfExp = null, ifExp = null;
foreach (var c in cases)
{
if (ifExp != null)
{
var prev = ifExp;
ifExp = CreateIfExpression(c.Condition, c.Case.Body);
prev.ElseBody.Add(ifExp);
}
else
{
rootIfExp = ifExp = CreateIfExpression(c.Condition, c.Case.Body);
}
}
if (switchExp.DefaultCase != null)
{
ifExp.ElseBody.AddRange(switchExp.DefaultCase);
}
return(new List <AphidExpression> {
idDecl, rootIfExp
});
}
private IExpression ParseIfExpression()
{
// 'if'
var expression = new IfExpression()
{
Token = currentToken
};
// '('
if (!ExpectPeek(TokenType.LParen))
{
return(null);
}
// ???
NextToken();
expression.Condition = ParseExpression(Precedence.Lowest);
// ')'
if (!ExpectPeek(TokenType.RParen))
{
return(null);
}
// '{'
if (!ExpectPeek(TokenType.LBrace))
{
return(null);
}
expression.Consequent = ParseBlockStatement();
// optional else
if (PeekTokenIs(TokenType.Else))
{
// 'else'
NextToken();
// '{'
if (!ExpectPeek(TokenType.LBrace))
{
return(null);
}
expression.Alternative = ParseBlockStatement();
}
return(expression);
}
public virtual T Visit(IfExpression expression)
{
foreach (var branch in expression.Branches)
{
branch.Condition.Accept(this);
branch.Block.Accept(this);
}
if (expression.Else != null)
{
expression.Else.Block.Accept(this);
}
return(default(T));
}
private void evalIfExpression(Object context, IfExpression ifExpression)
{
var condition = Eval(context, ifExpression.Condition);
if (condition is Bool succ)
{
if (succ.Value == true)
{
evalWithScope(ExecutionContext.Peek(), ifExpression.Consequence);
}
}
else
{
throw new System.Exception("Required a bool!");
}
}
private static IObject EvalIfExpression(IfExpression expression, Environment environment)
{
var condition = Evaluate(expression.Condition, environment);
if (IsError(condition))
{
return(condition);
}
if (IsTruthy(condition))
{
return(Evaluate(expression.Consequence, environment));
}
return(expression.Alternative != null?Evaluate(expression.Alternative, environment) : null);
}
private IExpression ParseIfExpression()
{
var ie = new IfExpression {
Token = CurToken
};
NextToken();
ie.Condition = ParseExpression(LOWEST);
ie.Consequence = ParseBlockStatement();
if (CurTokenIs(TokenType.Else))
{
ie.Alternative = ParseBlockStatement();
}
return(ie);
}
void PrintExpression(IfExpression e, int d)
{
SayLn("IfExpression(");
PrintExpression(e.Test, d + 1); SayLn(",");
PrintExpression(e.Then, d + 1);
if (e.Else != null)
{ /* else is optional */
SayLn(",");
PrintExpression(e.Else, d + 1);
}
Say(")");
}
public BinaryExpression(IfExpression e1, string op, IfExpression e2)
{
LeftChild = e1;
Operator = op;
RightChild = e2;
}
public UnaryExpression(string op, IfExpression e)
{
this.Operator = op;
this.Expression = e;
}