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You should be able to use the same function to check a narrowing fun.pdf
- 1. You should be able to use the same function to check a narrowing function return by adding a similar semantic action on the top level production for the whole function. Be sure that you have declared that the function_header and body productions carry a type attribute if your receive an error indicating that they have no declared type. In addition both require semantic actions that pass the type information up the parse tree. My issue is that my output says "Type Mismatch on Function Body" when it should say "Illegal Narrowing Function Return" heres the test case: -- Narrowing Function Return function main returns integer; b: integer is 6 * 2; begin if 8 < 0 then b + 3.0; else b * 4.6; endif; end; heres the expected output: --Narrowing Function Return function main returns integer; b: integer is 6 * 2; begin if 8 < 0 then b + 3.0; else b * 4.6; endif; end; Semantic Error, Illegal Narrowing Function Return Lexical Errors 0 Syntax Errors 0 Semantic Errors 1 Heres the output I'm getting: -- Narrowing Function Return
- 2. function main returns integer; b: integer is 6 * 2; begin if 8 < 0 then b + 3.0; else b * 4.6; endif; end; Semantic Error, Type Mismatch on Function Body Lexical Errors: 0 Syntax Errors: 0 Semantic Errors 1 heres my parser.y code: /* Compiler Theory and Design Duane J. Jarc */ %{ #include #include #include #include #include using namespace std; #include "types.h" #include "listing.h" #include "symbols.h" int yylex(); void yyerror(const char* message); Symbols symbols; Types case_return = INT_TYPE; Types current_function_return = INT_TYPE; %} %define parse.error verbose
- 3. %union { CharPtr iden; Types type; } %token IDENTIFIER %token INT_LITERAL REAL_LITERAL BOOL_LITERAL CASE ELSE IF ENDIF %token ADDOP MULOP RELOP ANDOP EXPOP REMOP OROP NOTOP %token BEGIN_ BOOLEAN END ENDREDUCE FUNCTION INTEGER IS REDUCE RETURNS %token ENDCASE OTHERS REAL ARROW THEN WHEN %type type statement_ statement variable parameter reductions expression binary relation term factor exponent unary primary case cases %type function %type function_header %type body %% function: function_header optional_variable body ; function_header: FUNCTION IDENTIFIER parameters RETURNS type { current_function_return = $5; checkAssignment($5, $1, "Function Return"); // Check for illegal narrowing } ';' | FUNCTION IDENTIFIER RETURNS type { current_function_return = $3; checkAssignment($3, $1, "Function Return"); // Check for illegal narrowing } ';' | error ';' { $$ = MISMATCH; }; optional_variable: optional_variable variable | %empty ; variable:
- 4. IDENTIFIER ':' type IS statement_ {checkAssignment($3, $5, "Variable Initialization"); if (symbols.find($1, $3)) appendError(DUPLICATE_IDENTIFIER, $1); else symbols.insert($1, $3);} | error ';' {$$ = MISMATCH;}; parameters: parameter optional_parameter; optional_parameter: optional_parameter ',' parameter | %empty ; parameter: IDENTIFIER ':' type { if(symbols.find($1, $$)) appendError(DUPLICATE_IDENTIFIER, $1); else symbols.insert($1, $3);} | error ';' {$$ = MISMATCH;}; type: INTEGER {$$ = INT_TYPE;} | BOOLEAN {$$ = BOOL_TYPE;} | REAL {$$ = REAL_TYPE;} ; body: BEGIN_ statement_ END ';' { // Check for illegal narrowing in the function body checkAssignment(current_function_return, $2, "Function Return"); }; statement_: statement ';' | error ';' {$$ = MISMATCH;} ; statement: expression | IF expression THEN statement_ ELSE statement_ ENDIF {$$ = checkIfThen($2, $4, $6);} | CASE expression IS cases OTHERS ARROW statement_ ENDCASE {$$ =
- 5. checkExpression($2); $$ = checkReturns(case_return, $7);}; | REDUCE operator reductions ENDREDUCE {$$ = $3;} ; cases: cases case {case_return = checkCases($2, case_return);}| %empty {$$ = NAN_TYPE;}; case: WHEN INT_LITERAL ARROW statement_ {$$ = $4;} ; reductions: reductions statement_ {$$ = checkArithmetic($1, $2);} | {$$ = INT_TYPE;} %empty; operator: ADDOP | RELOP | EXPOP | MULOP ; expression: expression OROP binary {$$ = checkLogical($1, $3);} | binary ; binary: binary ANDOP relation {$$ = checkLogical($1, $3);} | relation ; relation: relation RELOP term {$$ = checkRelational($1, $3);}| term ; term: term ADDOP factor {$$ = checkArithmetic($1, $3);} | factor ; factor: factor MULOP primary {$$ = checkArithmetic($1, $3);} | factor REMOP exponent {$$ = checkRemainder($1, $3);} | exponent ; exponent: unary | unary EXPOP primary {$$ = checkArithmetic($1, $3);} ;
- 6. unary: NOTOP primary {$$ = checkNegation($2);} | primary; primary: '(' expression ')' {$$ = $2;} | INT_LITERAL | BOOL_LITERAL | REAL_LITERAL | IDENTIFIER {if (!symbols.find($1, $$)) appendError(UNDECLARED, $1);} ; %% void yyerror(const char* message) { appendError(SYNTAX, message); } int main(int argc, char *argv[]) { firstLine(); yyparse(); lastLine(); return 0; } heres my types.cc code: // Compiler Theory and Design // Duane J. Jarc // This file contains the bodies of the type checking functions #include #include using namespace std; #include "types.h" #include "listing.h" void checkAssignment(Types lValue, Types rValue, string message) { if(rValue == MISMATCH) return; if(lValue == BOOL_TYPE && rValue != BOOL_TYPE || lValue!=BOOL_TYPE && rValue ==BOOL_TYPE){
- 7. appendError(GENERAL_SEMANTIC, "Type Mismatch on " + message); } else if((lValue == INT_TYPE && rValue == REAL_TYPE) || (lValue == REAL_TYPE && rValue == INT_TYPE)){ appendError(GENERAL_SEMANTIC, "Illegal Narrowing " + message); } } Types checkArithmetic(Types left, Types right) { if (left == MISMATCH || right == MISMATCH) return MISMATCH; if (left == BOOL_TYPE || right == BOOL_TYPE) { appendError(GENERAL_SEMANTIC, "Numeric Type Required"); return MISMATCH; } if (left == REAL_TYPE || right == REAL_TYPE) { return REAL_TYPE; } return INT_TYPE; } Types checkLogical(Types left, Types right) { if (left == MISMATCH || right == MISMATCH) return MISMATCH; if (left != BOOL_TYPE || right != BOOL_TYPE) { appendError(GENERAL_SEMANTIC, "Boolean Type Required"); return MISMATCH; } return BOOL_TYPE; } Types checkRemainder(Types left, Types right){ if (left == MISMATCH || right == MISMATCH) return MISMATCH; if (left == BOOL_TYPE || right == BOOL_TYPE){
- 8. appendError(GENERAL_SEMANTIC, "Remainder Operator Requires Integer Operands"); return MISMATCH; } if (left == REAL_TYPE || right == REAL_TYPE){ appendError(GENERAL_SEMANTIC, "Remainder Operator Requires Integer Operands"); return MISMATCH; } return INT_TYPE; } Types checkIfThen(Types expression, Types left, Types right){ if(expression != BOOL_TYPE){ appendError(GENERAL_SEMANTIC, "If Expression Must Be Boolean"); return MISMATCH; } if(left != right){ appendError(GENERAL_SEMANTIC, "If-Then Type Mismatch"); return MISMATCH; } return expression; } Types checkNegation(Types right){ if (right != BOOL_TYPE){ appendError(GENERAL_SEMANTIC, "Boolean Type Required"); return MISMATCH; } return BOOL_TYPE; } Types checkRelational(Types left, Types right){ if (checkArithmetic(left, right) == MISMATCH) return MISMATCH; return BOOL_TYPE; } Types checkExpression(Types expression){ if(expression!=INT_TYPE){ appendError(GENERAL_SEMANTIC, " Case expression Not Integer "); return MISMATCH;
- 9. } return INT_TYPE; } Types checkCases(Types case_, Types cases){ if (cases != INT_TYPE){ if( cases != NAN_TYPE && case_ != cases){ appendError(GENERAL_SEMANTIC, "Case Types Mismatch"); return MISMATCH; } } // if (case_ != INT_TYPE){ // appendError(GENERAL_SEMANTIC, "When Expression Not Integer"); // if (cases != NAN_TYPE && case_ == cases){ // return cases; // } // return case_; // } return NAN_TYPE; } Types checkReturns(Types cases, Types others){ if(others != INT_TYPE){ appendError(GENERAL_SEMANTIC, " Other Expression Not Integer"); return others; } if(cases != NAN_TYPE){ return cases; } return INT_TYPE; }