// // parser.cpp // // The purpose of this program is to convert an equation or expression in standard //algebraic form into Reversed Polish Notation RPN. Once in RPN, the expression is //evaluated and can be reevaluated many times. // // The software may freely be used. If you find any bugs, or have suggestions then email //me at: sdattalo@interstice.com // // More information about the program may be found on my web page: // // http://www.dattalo.com // // TSD 09JUL95 REV1 is Finally working // TSD 06APR96 Added some comments and documentation // Known problems // 1) There is no index out of range checks for any of the arrays. Probably should // encapsulate the indexing within a class. // 2) There is no protection against math errors like division by zero. // I added a 'signal()' routine to catch Floating Point Errors, but nothing but exiting // the program is done. // 3) The exponentiation operator '^' has the same priority as '*' and '/'. May not // be a problem. // 4) Undefined varaibles are not flagged as such. Consequently, when the parser first // encounters a variable that has not been defined, it defines the variable and // initializes it to zero. Definitely a 'C' no-no. //#include <assoc.h> //#include <dict.h> #include <iostream.h> #include <string.h> #include<ctype.h> #include<stdlib.h> #include<stdio.h> #include<math.h> #include<signal.h> #include "parser.h" #define LF 0x0a // Various trial cases. Note that some of these will cause floating point exceptions. //This is no bug with the program; it's simply because some of the variables have not //been defined. static char fpin[] = "1+sin(-cos(1-(-2)))-3"; //char *fpin = "ln(2*x*cos(w * t + phi) / ( 7.2e-3 - 3*sqrt(4 * a *(c + 9.1e+7)) ) )"; //char *fpin = "cosh(2*x*cos(w * t + phi) + 5 / (1 + sqrt(4.9)))"; //char *fpin = "((-2/7)+(5)*1)"; //char *fpin = "cos(1)+(2*3)-(4)"; //char *fpin = "6-(1-2)/3*4+5"; //char *fpin = "log10(PI^2)"; int lines = 0, _index = 0; char var[30],ch; /*------------------------------------------------------------*/ //db_error // // This function is a make-shift error printer. Given an error number, it will //initialize the global variable *str to point to some constant string that describes //the error. // void db_error(int err_no) { char *str; switch(err_no) { case 1: str = "Missing '{' after key word"; break; case 2: str = "Illegal keyword"; break; case 3: str = "Missing '}'"; break; case 4: str = "Parenthesis mismatch"; break; case 5: str = "Operator syntax"; break; case 6: str = "Misplaced ')'"; break; default: str = "Unknown"; } printf("\nERROR: %d Line # %d\n%s\n", err_no, lines, str); /*fclose(fpin);*/ exit(1); } /*-----------------------------------------------*/ //my_getc // // This routine returns the next non-white space character in the input stream. //Note that the global variable "index" keeps track of where we are in the stream. //2nd Note, The stream for now is a string. // int my_getc(char *fpin) { char ch; while ( isspace(ch =fpin[_index])) /* Remove any spaces */ _index++; if (ch) _index++; /* If not the end of line, advance index */ return(ch); } /*-----------------------------------------------*/ //my_ungetc // void my_ungetc(char c, char *fpin) { fpin[--_index] = c; } /*-----------------------------------------------*/ //comment // //Not used here. However, if you wish to parse a file with comments, then you can suit //this function to your needs. // int comment(char c) { if (c == '#') { while( (c = my_getc(fpin)) != '#' && c != 0) ; return c=='#'; } return(0); } /*-----------------------------------------------*/ //skipbl // //Skipbl is an abbreviation for skip blanks. This function is primarily used with //file inputs. void skipbl(void) { char ch; do if ((ch= my_getc(fpin))==LF) lines++; while(isspace(ch) || comment(ch)); my_ungetc(ch,fpin); } /*-----------------------------------------------*/ int is_letter( char c) { c &= 0x5f; /* convert lower case to upper case */ return( (c>='A') && (c<='Z') ); } /*-----------------------------------------------*/ // Note that braces and brackets are equivalent. Consequently, something like // (a+b] while looking stupid is o.k. int is_openparen( char c) { return( (c=='[') || (c=='(') ); } /*-----------------------------------------------*/ int is_closedparen( char c) { return( (c==']') || (c==')') ); } /*-----------------------------------------------*/ int is_number( char c) { return( ( (c>='0') && (c<='9') ) || (c=='.') ); } /*------------------------------------------------------------*/ //read_substring // // The purpose of this function is to read a string from fpin. A string //in this case is defined to be same as a legal C name, i.e. the first character //must be a letter, the remaining characters can be letters or numbers. // void read_substring(char *variable) { char ch; skipbl(); ch=my_getc(fpin); if(is_letter(ch)) // The First character must be a letter { *variable++=ch; do { ch = my_getc(fpin); *variable++ = ch; // The other characters can be alphanumeric } while(is_letter(ch)|| ( (ch>='0') && (ch<='9') ) ); } my_ungetc(ch,fpin); *--variable = 0; } /*------------------------------------------------------------*/ void add_variable(token *new_variable) { variable_list[number_of_variables++] = new_variable; } /*------------------------------------------------------------*/ // search_var_and_func // // This function will take the input string "function" and see if it exists in either //the function list or the variable list. If it is found in either one, then the pointer //to the list element is returned. Otherwise, a new variable is created and added to the //variable list. token * search_var_and_func(char *function) { int i; skipbl(); for(i=0; i<number_of_functions; ++i) { if(strcmp(function_list[i]->nameOf(), function) == 0) return(function_list[i]); } for(i=0; i<number_of_variables; ++i) if(strcmp(variable_list[i]->nameOf(), function) == 0) return(variable_list[i]); variable *t = new variable(function); add_variable(t ); return(t); } /*-----------------------------------------------*/ variable::variable(char * new_variable) { value = 0; length = strlen(new_variable); name_ptr = new char [length]; strcpy(name_ptr, new_variable); type = TT_operand; } /*-----------------------------------------------*/ FOP::FOP(char* string) { char *end_ptr; end_ptr = NULL; if(*string) { t = strtod(&string[_index], &end_ptr); _index += (strlen (&string[_index]) - strlen(end_ptr)); } else t=0.0; type = TT_operand; } /*-----------------------------------------------*/ class BOPL_plus : public BOPL { public: virtual void execute(void) { numeric_push(numeric_pop() + numeric_pop());} virtual char get_ASCII(void) const { return '+';} }; class BOPL_minus : public BOPL { public: virtual void execute(void) { numeric_push(-numeric_pop() + numeric_pop());} virtual char get_ASCII(void) const { return '-';} }; /*-----------------------------------------------*/ class BOPH_times : public BOPH { public: virtual void execute(void) { numeric_push(numeric_pop() * numeric_pop());} virtual char get_ASCII(void) const { return '*';} }; class BOPH_divide : public BOPH { public: virtual void execute(void) { double t=numeric_pop(); numeric_push(numeric_pop() /t );} virtual char get_ASCII(void) const { return '/';} }; class BOPH_exponentiate : public BOPH { public: virtual void execute(void) { double t=numeric_pop(); numeric_push(pow(numeric_pop(),t) );} virtual char get_ASCII(void) const { return '^';} }; /*-----------------------------------------------*/ class UOP_minus : public UOP { public: virtual void execute(void) { numeric_push(-numeric_pop());} virtual char get_ASCII(void) const { return '-';} }; /*-----------------------------------------------*/ // // Trig Functions // class function_cos : public function { public: virtual void execute(void) { numeric_push(cos(numeric_pop()));} virtual Pchar nameOf(void) const { return "cos";} }; class function_sin : public function { public: virtual void execute(void) { numeric_push(sin(numeric_pop()));} virtual Pchar nameOf(void) const { return "sin";} }; class function_tan : public function { public: virtual void execute(void) { numeric_push(tan(numeric_pop()));} virtual Pchar nameOf(void) const { return "tan";} }; class function_sec : public function { public: virtual void execute(void) { numeric_push(1/cos(numeric_pop()));} virtual Pchar nameOf(void) const { return "sec";} }; class function_csc : public function { public: virtual void execute(void) { numeric_push(1/sin(numeric_pop()));} virtual Pchar nameOf(void) const { return "csc";} }; class function_cot : public function { public: virtual void execute(void) { numeric_push(1/tan(numeric_pop()));} virtual Pchar nameOf(void) const { return "cot";} }; /*-----------------------------------------------*/ // // Inverse Trig Functions // class function_acos : public function { public: virtual void execute(void) { numeric_push(acos(numeric_pop()));} virtual Pchar nameOf(void) const { return "acos";} }; class function_asin : public function { public: virtual void execute(void) { numeric_push(asin(numeric_pop()));} virtual Pchar nameOf(void) const { return "asin";} }; class function_atan : public function { public: virtual void execute(void) { numeric_push(atan(numeric_pop()));} virtual Pchar nameOf(void) const { return "atan";} }; class function_asec : public function { public: virtual void execute(void) { numeric_push(acos(1/numeric_pop()));} virtual Pchar nameOf(void) const { return "asec";} }; class function_acsc : public function { public: virtual void execute(void) { numeric_push(asin(1/numeric_pop()));} virtual Pchar nameOf(void) const { return "acsc";} }; class function_acot : public function { public: virtual void execute(void) { numeric_push(3.141592653/2-atan(numeric_pop()));} virtual Pchar nameOf(void) const { return "acot";} }; /*-----------------------------------------------*/ class function_cosh : public function { public: virtual void execute(void) { numeric_push(cosh(numeric_pop()));} virtual Pchar nameOf(void) const { return "cosh";} }; class function_sinh : public function { public: virtual void execute(void) { numeric_push(sinh(numeric_pop()));} virtual Pchar nameOf(void) const { return "sinh";} }; class function_tanh : public function { public: virtual void execute(void) { numeric_push(tanh(numeric_pop()));} virtual Pchar nameOf(void) const { return "tanh";} }; class function_sech : public function { public: virtual void execute(void) { numeric_push(1/cosh(numeric_pop()));} virtual Pchar nameOf(void) const { return "sech";} }; class function_csch : public function { public: virtual void execute(void) { numeric_push(1/sinh(numeric_pop()));} virtual Pchar nameOf(void) const { return "csch";} }; class function_coth : public function { public: virtual void execute(void) { numeric_push(1/tanh(numeric_pop()));} virtual Pchar nameOf(void) const { return "coth";} }; class function_ln : public function { public: virtual void execute(void) { numeric_push(log(numeric_pop()));} virtual Pchar nameOf(void) const { return "ln";} }; class function_log : public function // Identical to "ln" { public: virtual void execute(void) { numeric_push(log(numeric_pop()));} virtual Pchar nameOf(void) const { return "log";} }; class function_log10 : public function { public: virtual void execute(void) { numeric_push(log10(numeric_pop()));} virtual Pchar nameOf(void) const { return "log10";} }; class function_exp : public function { public: virtual void execute(void) { numeric_push(exp(numeric_pop()));} virtual Pchar nameOf(void) const { return "exp";} }; class function_sqrt : public function { public: virtual void execute(void) { numeric_push(sqrt(numeric_pop()));} virtual Pchar nameOf(void) const { return "sqrt";} }; /*-----------------------------------------------*/ void tokenize(void) { int have_left_operand=0; int temp; do { ch = my_getc(fpin); switch(ch) { case '+': if(have_left_operand) the_array[token_index++] = new BOPL_plus(); break; case '-': if(have_left_operand) the_array[token_index++] = new BOPL_minus(); else the_array[token_index++] = new UOP_minus(); break; case '(': level++; have_left_operand=0; the_array[token_index++] = new open_parenthesis('('); break; case ')': level--; have_left_operand=1; the_array[token_index++] = new closed_parenthesis(ch); break; case '*': the_array[token_index++] = new BOPH_times(); break; case '/': the_array[token_index++] = new BOPH_divide(); break; case '^': the_array[token_index++] = new BOPH_exponentiate(); break; case '%': case '&': // the_array[token_index++] = new BOPH(ch); break; default: if(is_letter(ch)) { have_left_operand =1; my_ungetc(ch, fpin); read_substring(var); the_array[token_index++] = search_var_and_func(var); } if( is_number(ch)) { have_left_operand =1; my_ungetc(ch, fpin); the_array[token_index++] = new FOP(fpin); } } } while(ch); null_token *f = new null_token; the_array[token_index++] = f; } /*-----------------------------------------------*/ void push(int _index) { the_stack[stack_index++] = the_array[_index]; } /*-----------------------------------------------*/ PS_state parse(PS_state state) { do { state = the_array[t1++]->a_search(state); // state=search(state); } while( (state!=PS_search_end)&&(state!=PS_search_closed)); return(state); } void init_function_list(void) { number_of_functions = 0; function_list[number_of_functions++]= new function_cos(); function_list[number_of_functions++]= new function_sin(); function_list[number_of_functions++]= new function_tan(); function_list[number_of_functions++]= new function_sec(); function_list[number_of_functions++]= new function_csc(); function_list[number_of_functions++]= new function_cot(); function_list[number_of_functions++]= new function_acos(); function_list[number_of_functions++]= new function_asin(); function_list[number_of_functions++]= new function_atan(); function_list[number_of_functions++]= new function_asec(); function_list[number_of_functions++]= new function_acsc(); function_list[number_of_functions++]= new function_acot(); function_list[number_of_functions++]= new function_cosh(); function_list[number_of_functions++]= new function_sinh(); function_list[number_of_functions++]= new function_tanh(); function_list[number_of_functions++]= new function_sech(); function_list[number_of_functions++]= new function_csch(); function_list[number_of_functions++]= new function_coth(); function_list[number_of_functions++]= new function_exp(); function_list[number_of_functions++]= new function_ln(); function_list[number_of_functions++]= new function_log(); function_list[number_of_functions++]= new function_log10(); function_list[number_of_functions++]= new function_sqrt(); } /*-----------------------------------------------*/ void init_variable_list(void) { number_of_variables = 0; variable *v = new variable("ONE"); v->value = 1; variable_list[number_of_variables++] = v; v = new variable("ZERO"); v->value = 0; variable_list[number_of_variables++] = v; v = new variable("PI"); v->value = 3.141592653; variable_list[number_of_variables++] = v; } typedef void (*fptr)(int); void Catcher(int *reglist) { cout << "Floating Point Error"; exit(1); } /*-----------------------------------------------*/ void main(void) { int i; signal(SIGFPE, (fptr)Catcher ); //Define catcher for floating point errors. init_function_list(); //Initialize the user defineable function list init_variable_list(); // " " " variable list printf("\n%s\n", fpin); // tokenize(); if(level) db_error(4); for( i=0; i<token_index; i++) the_array[i]->printOn(); cout << "\nParsed Results\n"; t1=0; parse(PS_null); cout << '\n'; for(i=0; i<stack_index; i++) { the_stack[i]->printOn(); cout << ' '; } if(level) db_error(4); for(i=0; i<stack_index; i++) { the_stack[i]->execute(); } cout << '\n' << numeric_stack[0] << '\n'; }
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