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#pragma once
#include "Expr.h"
#include "Var.h"
#include "Block.h"
namespace storm {
namespace bs {
STORM_PKG(lang.bs);
/**
* A condition used in the if-statement and the loop.
*
* A condition in Basic Storm can provide a bit more functionality than just an
* expression. Conditions may also provide a single variable that is to be visible only in
* the "true" case of the conditional statement. This is used to implement "weak casts",
* i.e. casts that may fail. For this reason, the condition provides a 'result' member in
* addition to code generation. The generated code always produces a boolean expression, and
* if 'result' returned something other than 'null', that variable is initialized if the
* condition was true.
*/
class Condition : public ObjectOn<Compiler> {
STORM_ABSTRACT_CLASS;
public:
// Create.
STORM_CTOR Condition();
// Get a suitable position for this condition.
virtual SrcPos STORM_FN pos();
// Get the variable that will be created by this condition if it is successful.
virtual MAYBE(LocalVar *) STORM_FN result();
// Generate code for the condition. This will create and initialize the "result"
// variable, if applicable. Will return a boolean value as the CodeResult value.
virtual void STORM_FN code(CodeGen *state, CodeResult *ok) ABSTRACT;
// Generate code to initialize 'result' in the true branch. It is possible to assume
// that 'code' was called previously.
virtual void STORM_FN trueCode(CodeGen *state);
};
/**
* A regular boolean condition.
*/
class BoolCondition : public Condition {
STORM_CLASS;
public:
// Create.
STORM_CTOR BoolCondition(Expr *expr);
// Get a suitable position for this condition.
virtual SrcPos STORM_FN pos();
// Result variable.
virtual MAYBE(LocalVar *) STORM_FN result();
// Generate code.
virtual void STORM_FN code(CodeGen *state, CodeResult *ok);
// To string.
virtual void STORM_FN toS(StrBuf *to) const;
private:
// The expression we're evaluating.
Expr *expr;
};
// Create a suitable condition for an expression.
// TODO: Make this extensible somehow!
Condition *STORM_FN createCondition(Expr *expr);
/**
* A block used to encapsulate the additional variable created by a successful weak cast.
*
* It also ensures to call the "trueCode" inside a condition as necessary.
*/
class CondSuccess : public Block {
STORM_CLASS;
public:
STORM_CTOR CondSuccess(SrcPos pos, Block *parent, Condition *cond);
// Set the single contained expression. Throws if used more than once.
void STORM_FN set(Expr *expr);
// Result.
virtual ExprResult STORM_FN result();
// Code generation.
virtual void STORM_FN blockCode(CodeGen *state, CodeResult *to);
// Auto casting.
virtual Int STORM_FN castPenalty(Value to);
// Anythin set?
Bool STORM_FN any() const { return expr != null; }
Bool STORM_FN empty() const { return expr == null; }
// To string.
virtual void STORM_FN toS(StrBuf *to) const;
private:
// Associated condition.
Condition *cond;
// Contained expression.
MAYBE(Expr *) expr;
};
}
}
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