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interpreter.y
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interpreter.y
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%{
#include "structs_interpreter.hpp"
#include <iostream>
#include <iomanip>
//---- Function declarations to use in lex file
int yylex();
int yyerror(const char*);
//---- Global variables
std::map<std::string, double> variables;
static int dummy = 0;
unsigned int line = 1;
unsigned int column = 1;
bool debug;
//---- Functions
inline int check_variable_declaration(const std::string& variableName);
inline void execute_instruction(std::vector<Instruction>& instructions, const int i, int& i_ref);
%}
%union {
double fVal;
std::string* str;
std::vector<Instruction>* Instructions;
Equation* equation;
};
/*---- Nonterminals ----*/
%start PROGRAM
%type<equation> EQUATION
%type<Instructions> ASSIGNMENT
%type<Instructions> INSTRUCTIONS
%type<Instructions> INSTRUCTIONS_MULTI
%type<str> VARIABLE
%type<str> OPERATOR
/*---- Tokens with type ----*/
%token <fVal> NUMBER
%token <str> TEXT
%token <str> VARNAME
%token <str> COMPARATOR
/*---- Tokens without type ----*/
%token PRINT
%token IF
%token WHILE
%token NEWLINE
%token UNK
%%
/*---- Rules - S ----*/
PROGRAM : PROGRAM INSTRUCTIONS ';' {
std::cout << std::setprecision(15);
if(!$2->empty()) { execute_instruction(*$2, 0, dummy); }
delete $2;
}
| PROGRAM INSTRUCTIONS { return yyerror("expected ';' at the end of instruction"); }
| PROGRAM INSTRUCTIONS NEWLINE { line--; column--; return yyerror("expected ';' at the end of instruction"); }
| PROGRAM NEWLINE { column = 1; }
| /*nic*/
;
/*---- Rules - OPERATOR ----*/
OPERATOR : '+' { $$ = new std::string("+"); }
| '-' { $$ = new std::string("-"); }
| '*' { $$ = new std::string("*"); }
| '/' { $$ = new std::string("/"); }
| '^' { $$ = new std::string("^"); }
;
/*---- Rules - INSTRUCTIONS_MULTI ----*/
INSTRUCTIONS_MULTI : INSTRUCTIONS_MULTI INSTRUCTIONS ';' { $$->insert($$->end(), $2->begin(), $2->end()); }
| INSTRUCTIONS_MULTI INSTRUCTIONS { line--; column--; return yyerror("expected ';' at the end of instruction"); }
| INSTRUCTIONS_MULTI NEWLINE { column = 1; }
| /*nic*/{
$$ = new std::vector<Instruction>();
}
;
/*---- Rules - INSTRUCTIONS ----*/
INSTRUCTIONS : PRINT '(' EQUATION ')' {
$$ = new std::vector<Instruction>(1);
(*$$)[0].equations.push_back(*$3); delete $3;
(*$$)[0].type = PRINT_;
}
| PRINT '(' TEXT ')' {
$$ = new std::vector<Instruction>(1);
(*$$)[0].var = *$3; delete $3;
(*$$)[0].type = PRINT_TEXT;
}
| ASSIGNMENT { $$ = $1; }
| IF '(' EQUATION COMPARATOR EQUATION ')' INSTRUCTIONS {
$$ = $7;
Instruction temp;
temp.equations.push_back(*$3); delete $3;
temp.equations.push_back(*$5); delete $5;
temp.type = IF_;
temp.comparator = *$4; delete $4;
$$->insert($$->begin(), temp);
}
| IF '(' EQUATION COMPARATOR EQUATION ')' '{' INSTRUCTIONS_MULTI '}' {
$$ = $8;
Instruction temp;
temp.equations.push_back(*$3); delete $3;
temp.equations.push_back(*$5); delete $5;
temp.type = IF_;
temp.instructions_inside = $8->size();
temp.comparator = *$4; delete $4;
$$->insert($$->begin(), temp);
}
| WHILE '(' VARIABLE ',' ASSIGNMENT ')' INSTRUCTIONS {
$$ = $7;
if(*$3 != (*$5)[0].var) { return yyerror("wrong second argument in WHILE"); }
$$->insert($$->begin(), $5->begin(), $5->end()); delete $5;
Instruction temp;
temp.type = WHILE_;
temp.instructions_inside += 1;
temp.var = *$3; delete $3;
$$->insert($$->begin(), temp);
}
| WHILE '(' VARIABLE ',' ASSIGNMENT ')' '{' INSTRUCTIONS_MULTI '}' {
$$ = $8;
if(*$3 != (*$5)[0].var) { return yyerror("wrong second argument in WHILE"); }
$$->insert($$->begin(), $5->begin(), $5->end()); delete $5;
Instruction temp;
temp.type = WHILE_;
temp.instructions_inside = $8->size();
temp.var = *$3; delete $3;
$$->insert($$->begin(), temp);
}
;
/*---- Rules - ASSIGNMENT ----*/
ASSIGNMENT : VARNAME '=' EQUATION {
variables[*$1];
$$ = new std::vector<Instruction>(1);
(*$$)[0].equations.push_back(*$3); delete $3;
(*$$)[0].type = ASSIGNMENT_;
(*$$)[0].var = *$1; delete $1;
}
;
/*---- Rules - EQUATION ----*/
EQUATION : NUMBER {
$$ = new Equation();
($$->elements.end()-1)->val = $1;
}
| '-' NUMBER {
$$ = new Equation();
($$->elements.end()-1)->val = -$2;
}
| VARIABLE {
$$ = new Equation();
($$->elements.end()-1)->var = *$1 + "+"; delete $1;
}
| '-' VARIABLE {
$$ = new Equation();
($$->elements.end()-1)->var = *$2 + "-"; delete $2;
}
| EQUATION OPERATOR NUMBER {
$$->elements_size_increase();
($$->elements.end()-2)->operation = *$2; delete $2;
($$->elements.end()-1)->val = $3;
}
| EQUATION OPERATOR '-' NUMBER {
$$->elements_size_increase();
($$->elements.end()-2)->operation = *$2; delete $2;
($$->elements.end()-1)->val = -$4;
}
| EQUATION OPERATOR VARIABLE {
$$->elements_size_increase();
($$->elements.end()-2)->operation = *$2; delete $2;
($$->elements.end()-1)->var = *$3 + "+"; delete $3;
}
| EQUATION OPERATOR '-' VARIABLE {
$$->elements_size_increase();
($$->elements.end()-2)->operation = *$2; delete $2;
($$->elements.end()-1)->var = *$4 + "-"; delete $4;
}
;
/*---- Rules - VARIABLE ----*/
VARIABLE : VARNAME {
if(check_variable_declaration(*$1) == 1) { return 1; }
$$ = $1;
}
;
%%
/*
* Checks if variable is declared.
*
* @pa variableName Name of variable to check.
* @return Comparison result.
*/
int check_variable_declaration(const std::string& variableName) {
if(variables.find(variableName) == variables.end()) {
const std::string message("variable undeclared " + variableName);
return yyerror(message.c_str());
}
return 0;
}
//---- Instruction execution functions
/*
* Executes comparison between left and right operands.
*
* @param left Left operand.
* @param operation comparator.
* @param Right operand.
* @return Comparison result.
*/
bool compare (const double& left, const std::string& comparator, const double& right) {
if(comparator == "==") { return left == right; }
else if(comparator == "!=") { return left != right; }
else if(comparator == ">") { return left > right; }
else if(comparator == ">=") { return left >= right; }
else if(comparator == "<") { return left < right; }
else if(comparator == "<=") { return left <= right; }
return false;
}
/*
* Returns variable value.
*
* @param variableName Name of variable.
* @return Variable value.
*/
double get_variable_value(const std::string& variableName){
std::string temp_var = variableName;
const char var_sign = *(temp_var.end()-1);
temp_var.pop_back();
double result = variables[temp_var];
if(var_sign == '-') { result = -result; }
return result;
}
/*
* Selects action for instruction type and executes it.
*
* @param instructions Set of instructions to execute.
* @param i Current position in set.
* @param i_ref Changeable position. Used in recurrence to prevent multiple instruction executions.
* @return void.
*/
void execute_instruction(std::vector<Instruction>& instructions, const int i, int& i_ref) {
switch(instructions[i].type) {
case ASSIGNMENT_ : {
variables[instructions[i].var] = instructions[i].calculate(0);
if(debug) { std::cout << "Variable " << instructions[i].var << " has value of " << variables[instructions[i].var] << "\n"; }
break;
} //end ASSIGN
case PRINT_ : {
std::cout << ( debug? "PRINT: " : "") << instructions[i].calculate(0) << "\n";
break;
} //end PRINT
case PRINT_TEXT : {
std::cout << ( debug? "PRINT: " : "") << instructions[i].var << "\n";
break;
} //end PRINT_TEXT
case IF_ : {
const double left = instructions[i].calculate(0);
const double right = instructions[i].calculate(1);
if(debug) { std::cout << left << " " + instructions[i].comparator + " " << right << ": "; }
i_ref += 1 + instructions[i].instructions_inside;
if(compare(left, instructions[i].comparator, right)) {
if(debug) { std::cout << "TRUE\n"; }
for(int j = i + 1; j < i + 1 + instructions[i].instructions_inside; j++) {
execute_instruction(instructions, j, j);
}
}
else { if(debug) { std::cout << "FALSE\n"; } }
break;
} //end IF
case WHILE_ : {
if(debug) { std::cout << "\nLoop start\n"; }
const std::string var = instructions[i].var;
i_ref += instructions[i].instructions_inside;
while(variables[var] != 0) {
for(int j = i + 2; j < i + 1 + instructions[i].instructions_inside; j++) {
execute_instruction(instructions, j, j);
}
//std::cout << "Execution finish\n";
variables[var] = instructions[i + 1].calculate(0);
if(debug) { std::cout << "Variable " << var << " has value of " << variables[var] << "\n"; }
}
if(debug) { std::cout << "Loop end\n\n"; }
break;
} //end WHILE
} //end switch
dummy = 0;
}