/// <summary>
/// Gets a null denotation token for given token using the null denotation getter.
/// </summary>
/// <param name="self"></param>
/// <returns></returns>
public Token GetNullDenotation(Token self)
{
if (this.NullDenotationGetter == null)
throw new InvalidOperationException("Unable to invoke null denotation getter: getter is not set.");
if (self.Type != this.TokenType)
throw new ArgumentException("Unable to invoke null denotation getter: invalid self type.", "self");
return this.NullDenotationGetter(self);
}
/// <summary>
/// Initializes a new instance of the <see cref="Token"/> class with given NumPlurals and abstract syntax tree.
/// </summary>
/// <param name="numPlurals"></param>
/// <param name="astRoot">Abstract syntax tree root.</param>
public AstPluralRule(int numPlurals, Token astRoot)
{
if (numPlurals <= 0)
throw new ArgumentOutOfRangeException("numPlurals");
if (astRoot == null)
throw new ArgumentNullException("astRoot");
this.NumPlurals = numPlurals;
this.AstRoot = astRoot;
}
/// <summary>
/// Compiles a plural rule abstract syntax tree into managed dynamic method delegate using an IL code generator.
/// </summary>
/// <param name="astRoot">abstract syntax tree root node.</param>
/// <param name="outputDelegateType">Type of output delegate.</param>
/// <returns>Compiled dynamic method of given type.</returns>
public virtual Delegate CompileToDynamicMethod(Token astRoot, Type outputDelegateType)
{
var dynamicMethod = this.CreateDynamicMethod(outputDelegateType);
var il = dynamicMethod.GetILGenerator();
this.CompileStart(il);
this.CompileNode(il, astRoot);
this.CompileFinish(il);
return dynamicMethod.CreateDelegate(outputDelegateType);
}
/// <summary>
/// Recursively compiles an AST node to the IL instructions.
/// </summary>
/// <param name="il">IL generator instance.</param>
/// <param name="node">AST node.</param>
protected virtual void CompileNode(ILGenerator il, Token node)
{
switch (node.Type)
{
case TokenType.Number:
il.Emit(OpCodes.Ldc_I8, node.Value);
break;
case TokenType.N:
il.Emit(OpCodes.Ldarg_0);
break;
case TokenType.Plus:
this.CompileNode(il, node.Children[0]);
this.CompileNode(il, node.Children[1]);
il.Emit(OpCodes.Add);
break;
case TokenType.Minus:
this.CompileNode(il, node.Children[0]);
this.CompileNode(il, node.Children[1]);
il.Emit(OpCodes.Sub);
break;
case TokenType.Divide:
this.CompileNode(il, node.Children[0]);
this.CompileNode(il, node.Children[1]);
il.Emit(OpCodes.Div);
break;
case TokenType.Multiply:
this.CompileNode(il, node.Children[0]);
this.CompileNode(il, node.Children[1]);
il.Emit(OpCodes.Mul);
break;
case TokenType.Modulo:
this.CompileNode(il, node.Children[0]);
this.CompileNode(il, node.Children[1]);
il.Emit(OpCodes.Rem);
break;
case TokenType.GreaterThan:
this.CompileNode(il, node.Children[0]);
this.CompileNode(il, node.Children[1]);
this.EmitConditionalValue(il, OpCodes.Bgt);
break;
case TokenType.GreaterOrEquals:
this.CompileNode(il, node.Children[0]);
this.CompileNode(il, node.Children[1]);
this.EmitConditionalValue(il, OpCodes.Bge);
break;
case TokenType.LessThan:
this.CompileNode(il, node.Children[0]);
this.CompileNode(il, node.Children[1]);
this.EmitConditionalValue(il, OpCodes.Blt);
break;
case TokenType.LessOrEquals:
this.CompileNode(il, node.Children[0]);
this.CompileNode(il, node.Children[1]);
this.EmitConditionalValue(il, OpCodes.Ble);
break;
case TokenType.Equals:
this.CompileNode(il, node.Children[0]);
this.CompileNode(il, node.Children[1]);
this.EmitConditionalValue(il, OpCodes.Beq);
break;
case TokenType.NotEquals:
this.CompileNode(il, node.Children[0]);
this.CompileNode(il, node.Children[1]);
this.EmitConditionalValue(il, OpCodes.Beq, 0, 1);
break;
case TokenType.And:
this.CompileNode(il, node.Children[0]);
this.CompileNode(il, node.Children[1]);
il.Emit(OpCodes.And);
break;
case TokenType.Or:
this.CompileNode(il, node.Children[0]);
this.CompileNode(il, node.Children[1]);
il.Emit(OpCodes.Or);
break;
case TokenType.Not:
this.CompileNode(il, node.Children[0]);
this.EmitConditionalValue(il, OpCodes.Brfalse);
break;
case TokenType.TernaryIf:
this.CompileNode(il, node.Children[0]);
this.EmitConditionalBranch(il, OpCodes.Brtrue, node.Children[1], node.Children[2]);
break;
}
}
/// <summary>
/// Emits instructions required for conditional branch using given OpCode to check condition and given nodes for positive and negative branches.
/// </summary>
/// <param name="il">IL generator instance.</param>
/// <param name="conditionOpCode">OpCode of the condition check operation.</param>
/// <param name="trueNode">AST node that will be executed when condition returns positive result.</param>
/// <param name="falseNode">AST node that will be executed when condition returns negative result.</param>
protected virtual void EmitConditionalBranch(ILGenerator il, OpCode conditionOpCode, Token trueNode, Token falseNode)
{
var trueLabel = il.DefineLabel();
var endLabel = il.DefineLabel();
il.Emit(conditionOpCode, trueLabel);
this.CompileNode(il, falseNode);
il.Emit(OpCodes.Br, endLabel);
il.MarkLabel(trueLabel);
this.CompileNode(il, trueNode);
il.MarkLabel(endLabel);
}
protected long Evaluate(Token node, long number)
{
switch (node.Type)
{
case TokenType.Number:
return node.Value;
case TokenType.N:
return number;
case TokenType.Plus:
return this.Evaluate(node.Children[0], number)
+ this.Evaluate(node.Children[1], number);
case TokenType.Minus:
return this.Evaluate(node.Children[0], number)
- this.Evaluate(node.Children[1], number);
case TokenType.Divide:
return this.Evaluate(node.Children[0], number)
/ this.Evaluate(node.Children[1], number);
case TokenType.Multiply:
return this.Evaluate(node.Children[0], number)
* this.Evaluate(node.Children[1], number);
case TokenType.Modulo:
return this.Evaluate(node.Children[0], number)
% this.Evaluate(node.Children[1], number);
case TokenType.GreaterThan:
return this.Evaluate(node.Children[0], number)
> this.Evaluate(node.Children[1], number)
? 1 : 0;
case TokenType.GreaterOrEquals:
return this.Evaluate(node.Children[0], number)
>= this.Evaluate(node.Children[1], number)
? 1 : 0;
case TokenType.LessThan:
return this.Evaluate(node.Children[0], number)
< this.Evaluate(node.Children[1], number)
? 1 : 0;
case TokenType.LessOrEquals:
return this.Evaluate(node.Children[0], number)
<= this.Evaluate(node.Children[1], number)
? 1 : 0;
case TokenType.Equals:
return this.Evaluate(node.Children[0], number)
== this.Evaluate(node.Children[1], number)
? 1 : 0;
case TokenType.NotEquals:
return this.Evaluate(node.Children[0], number)
!= this.Evaluate(node.Children[1], number)
? 1 : 0;
case TokenType.And:
return this.Evaluate(node.Children[0], number) != 0
&& this.Evaluate(node.Children[1], number) != 0
? 1 : 0;
case TokenType.Or:
return this.Evaluate(node.Children[0], number) != 0
|| this.Evaluate(node.Children[1], number) != 0
? 1 : 0;
case TokenType.Not:
return this.Evaluate(node.Children[0], number) == 0
? 1 : 0;
case TokenType.TernaryIf:
return this.Evaluate(node.Children[0], number) != 0
? this.Evaluate(node.Children[1], number)
: this.Evaluate(node.Children[2], number);
default:
throw new InvalidOperationException(String.Format("Can not evaluate token: {0}.", node.Type));
}
}
/// <summary>
/// Parses the input string that contains a plural rule formula and generates an abstract syntax tree.
/// </summary>
/// <param name="input">Input string.</param>
/// <returns>Root node of the abstract syntax tree.</returns>
public Token Parse(string input)
{
this.Input = input + "\0";
this.Position = 0;
this.CurrentToken = this.GetNextToken();
return this.ParseNextExpression();
}
protected Token ParseNextExpression(int rightBindingPower = 0)
{
var token = this.CurrentToken;
this.CurrentToken = this.GetNextToken();
var left = this.GetDefinition(token.Type).GetNullDenotation(token);
while (rightBindingPower < this.GetDefinition(this.CurrentToken.Type).LeftBindingPower)
{
token = this.CurrentToken;
this.CurrentToken = this.GetNextToken();
left = this.GetDefinition(token.Type).GetLeftDenotation(token, left);
}
return left;
}
protected void AdvancePosition()
{
this.CurrentToken = this.GetNextToken();
}