source: src/Common/Eval.cc @ ec92b48

//
// Cforall Version 1.0.0 Copyright (C) 2015 University of Waterloo
//
// The contents of this file are covered under the licence agreement in the
// file "LICENCE" distributed with Cforall.
//
// utility.h --
//
// Author           : Richard C. Bilson
// Created On       : Mon May 18 07:44:20 2015
// Last Modified By : Peter A. Buhr
// Last Modified On : Sun May  6 22:24:16 2018
// Update Count     : 40
//

#include <utility> // for pair

#include "Common/PassVisitor.h"
#include "InitTweak/InitTweak.h"
#include "SynTree/Expression.h"

struct Eval : public WithShortCircuiting {
        long long int value = 0;
        bool valid = true;

        void previsit( BaseSyntaxNode * ) { visit_children = false; }
        void postvisit( BaseSyntaxNode * ) { valid = false; }

        void postvisit( ConstantExpr * expr ) {
                value = expr->intValue();
        }

        void postvisit( CastExpr * expr ) {
                auto arg = eval(expr->arg);
                valid = arg.second;
                value = arg.first;
                // TODO: perform type conversion on value if valid
        }

        void postvisit( VariableExpr * expr ) {
                if ( EnumInstType * inst = dynamic_cast<EnumInstType *>(expr->result) ) {
                        if ( EnumDecl * decl = inst->baseEnum ) {
                                if ( decl->valueOf( expr->var, value ) ) { // value filled by valueOf
                                        return;
                                }
                        }
                }
                valid = false;
        }

        void postvisit( ApplicationExpr * expr ) {
                DeclarationWithType * function = InitTweak::getFunction(expr);
                if ( ! function || function->linkage != LinkageSpec::Intrinsic ) { valid = false; return; }
                const std::string & fname = function->name;
                assertf( expr->args.size() == 1 || expr->args.size() == 2, "Intrinsic function with %zd arguments: %s", expr->args.size(), fname.c_str() );
                std::pair<long long int, bool> arg1, arg2;
                arg1 = eval(expr->args.front());
                valid = valid && arg1.second;
                if ( ! valid ) return;
                if ( expr->args.size() == 2 ) {
                        arg2 = eval(expr->args.back());
                        valid = valid && arg2.second;
                        if ( ! valid ) return;
                }
                if (fname == "?+?") {
                        value = arg1.first + arg2.first;
                } else if (fname == "?-?") {
                        value = arg1.first - arg2.first;
                } else if (fname == "?*?") {
                        value = arg1.first * arg2.first;
                } else if (fname == "?/?") {
                        value = arg1.first / arg2.first;
                } else if (fname == "?%?") {
                        value = arg1.first % arg2.first;
                } else {
                        valid = false;
                }
                // TODO: implement other intrinsic functions
        }
};

std::pair<long long int, bool> eval(Expression * expr) {
        PassVisitor<Eval> ev;
        if (expr) {
                expr->accept(ev);
                return std::make_pair(ev.pass.value, ev.pass.valid);
        } else {
                return std::make_pair(0, false);
        }
}

// Local Variables: //
// tab-width: 4 //
// mode: c++ //
// compile-command: "make install" //
// End: //