/disk1/scratch/aselle/projects/seexpr/SeExpr/src/demos/asciiCalculator.cpp

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/*
* (c) Disney Enterprises, Inc.  All rights reserved.
*
* This file is licensed under the terms of the Microsoft Public License (MS-PL)
* as defined at: http://opensource.org/licenses/MS-PL.
*
* A complete copy of this license is included in this distribution as the file
* LICENSE.
*/
#include <SeExpression.h>
#include <cstdlib>
#include <cstdio>
#include <cstring>

#define STACK_DEPTH 256                                                                                                                                                                            


class CalculatorExpr : public SeExpression
{
public:
    CalculatorExpr(const std::string& expr)
        :SeExpression(expr), _count(0)
    {
        for(int i = 0; i < STACK_DEPTH; i++) {
            stack[i].val = SeVec3d(0.0);
            fail_stack[i] = false;
        };
    };
    
    CalculatorExpr()
        :SeExpression(), _count(0)
    {
        for(int i = 0; i < STACK_DEPTH; i++)
            fail_stack[i] = false;
    };
    
    void push() {
        stack[_count].val = evaluate();
        _count++;
    };
    
    void fail_push() {
        fail_stack[_count] = true;
        stack[_count].val = SeVec3d(0.0);
        _count++;
    };
    
    int count() const { return _count; };
    
private:
    struct SimpleVar:public SeExprVectorVarRef
    {
        SimpleVar()
            :val(SeVec3d(0.0))
        {}
        
        SeVec3d val; // independent variable
        
        void eval(const SeExprVarNode* /*node*/,SeVec3d& result)
        {
            result = val;
        }
    };
    
    mutable SimpleVar stack     [STACK_DEPTH];
    mutable bool      fail_stack[STACK_DEPTH];
    mutable int       _count;
    
    SeExprVarRef* resolveVar(const std::string& name) const {
        if(name[0] == '_') {
            int position = atoi(name.substr(1,name.size() - 1).c_str());
            if(position >= count())
                std::cerr << "Use of unused result line." << std::endl;
            if(fail_stack[position])
                std::cerr << "Use of invalid result line." << std::endl;
            return &(stack[position]);
        };
        return 0;
    };
};


void quit(const std::string & str) {
    if(str == "quit"
       || str == "q")
        exit(0);
};


int main()
{
    CalculatorExpr expr;
    std::string str;
    
    std::cout << "SeExpr Basic Calculator";
    
    while(true) {
        std::cout << std::endl << expr.count() << "> ";
        //std::cin >> str;
        getline(std::cin, str);
        
        if(std::cin.eof()) {
            std::cout << std::endl;
            str = "q";
        };
        
        quit(str);
        expr.setWantVec(true);
        expr.setExpr(str);
        
        if(!expr.isValid()) {
            expr.fail_push();
            std::cerr << "Expression failed: " << expr.parseError() << std::endl;
        } else {
            expr.push();
            std::cout << "   " << expr.evaluate();
        };
    };
    
    return 0;
}

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