/* This file is part of the Project Athena Zephyr Notification System. * It is one of the source files comprising zwgc, the Zephyr WindowGram * client. * * Created by: Marc Horowitz * * $Source: /mit/zephyr/repository/zephyr/clients/zwgc/eval.c,v $ * $Author: ghudson $ * * Copyright (c) 1989 by the Massachusetts Institute of Technology. * For copying and distribution information, see the file * "mit-copyright.h". */ #include #if (!defined(lint) && !defined(SABER)) static const char rcsid_eval_c[] = "$Id: eval.c,v 1.6 1995/07/07 21:59:28 ghudson Exp $"; #endif #include /****************************************************************************/ /* */ /* Code to evaluate an expression: */ /* */ /****************************************************************************/ #include #include "new_memory.h" #include "node.h" #include "eval.h" #include "substitute.h" #include "port.h" #include "buffer.h" #include "regexp.h" #include "text_operations.h" #include "zwgc.h" #include "variables.h" /****************************************************************************/ /* */ /* Code to deal with string/boolean conversion: */ /* */ /****************************************************************************/ /* * Internal Routine: * * int string_to_bool(string str) * Effects: Returns true iff the string str represents true. * True is represented by any string which is equal to * "true" when case is disregraded. */ #define string_to_bool(str) (!strcasecmp(str,"true")) /* * Internal Routine: * * string bool_to_string(int bool) * Effects: Returns a string representive for the C boolean bool. * (In C, true == non-zero) I.e., * string_to_bool(bool_to_string(x)) == !!x. * The string returned is on the heap & must be freed * eventually. */ static string bool_to_string(bool) int bool; { return(bool ? string_Copy("TRUE") : string_Copy("FALSE")); } /* * int eval_bool_expr(Node *expr) * Modifies: dict * Requires: expr is a proper expression or NULL. (see node.c) * Effects: Evaluates expr to its boolean value which is returned. * NULL is defined to have the boolean value true. */ int eval_bool_expr(expr) Node *expr; { string temp; int result; if (!expr) return(1); temp = eval_expr(expr); result = string_to_bool(temp); free(temp); return(result); } /****************************************************************************/ /* */ /* Code to evaluate an expression: */ /* */ /****************************************************************************/ /* * string eval_expr(Node *expr) * Modifies: dict * Requires: expr is a proper expression (NOT NULL). (see node.c) * Effects: Evaluates expr to its string value which is returned. * The returned string is on the heap and must be freed * eventually. */ string eval_expr(expr) Node *expr; { int opcode = expr->opcode; int bool_result; string first, second; char *result; string *text_ptr; char *getenv(); /* UNIX get environment variable function */ /* * Dispatch based on the opcode of the top node in the expression: */ switch (opcode) { case STRING_CONSTANT_OPCODE: return(string_Copy(expr->d.string_constant)); case VARREF_OPCODE: return(string_Copy(var_get_variable(expr->d.string_constant))); case BUFFER_OPCODE: return(string_Copy(buffer_to_string())); /* * Handle unary expressions: */ case NOT_OPCODE: case SUBSTITUTE_OPCODE: case PROTECT_OPCODE: case VERBATIM_OPCODE: case GETENV_OPCODE: case UPCASE_OPCODE: case DOWNCASE_OPCODE: case ZVAR_OPCODE: case GET_OPCODE: first = eval_expr(expr->d.nodes.first); switch (opcode) { case NOT_OPCODE: result = bool_to_string(! string_to_bool(first)); break; case SUBSTITUTE_OPCODE: result = substitute(var_get_variable, first); break; case PROTECT_OPCODE: result=protect(first); break; case VERBATIM_OPCODE: return(verbatim(first,0)); case GETENV_OPCODE: result = getenv(first); if (!result) result = string_Copy(""); else result = string_Copy(result); break; case UPCASE_OPCODE: return(string_Upcase(first)); case DOWNCASE_OPCODE: return(string_Downcase(first)); case ZVAR_OPCODE: result = ZGetVariable(first); if (!result) result = string_Copy(""); else result = string_Copy(result); break; case GET_OPCODE: result = read_from_port(first); break; } free(first); break; /* * Handle binary operators: */ case PLUS_OPCODE: case AND_OPCODE: case OR_OPCODE: case EQ_OPCODE: case NEQ_OPCODE: case REGEQ_OPCODE: case REGNEQ_OPCODE: first = eval_expr(expr->d.nodes.first); second = eval_expr(expr->d.nodes.second); switch (opcode) { case PLUS_OPCODE: result = string_Concat(first, second); free(first); free(second); return(result); case AND_OPCODE: bool_result = string_to_bool(first) && string_to_bool(second); break; case OR_OPCODE: bool_result = string_to_bool(first) || string_to_bool(second); break; case EQ_OPCODE: bool_result = string_Eq(first, second); break; case NEQ_OPCODE: bool_result = string_Neq(first, second); break; case REGEQ_OPCODE: bool_result = ed_regexp_match_p(first, second); break; case REGNEQ_OPCODE: bool_result = !ed_regexp_match_p(first, second); break; } free(first); free(second); result = bool_to_string(bool_result); break; /* * Handle text-manipulation operators: */ case LANY_OPCODE: case RANY_OPCODE: case LBREAK_OPCODE: case RBREAK_OPCODE: case LSPAN_OPCODE: case RSPAN_OPCODE: first = eval_expr(expr->d.nodes.first); second = eval_expr(expr->d.nodes.second); text_ptr = &first; switch (opcode) { case LANY_OPCODE: result = lany(text_ptr, second); break; case RANY_OPCODE: result = rany(text_ptr, second); break; case LBREAK_OPCODE: result = lbreak(text_ptr, string_to_character_class(second)); break; case RBREAK_OPCODE: result = rbreak(text_ptr, string_to_character_class(second)); break; case LSPAN_OPCODE: result = lspan(text_ptr, string_to_character_class(second)); break; case RSPAN_OPCODE: result = rspan(text_ptr, string_to_character_class(second)); break; } if (expr->d.nodes.first->opcode == VARREF_OPCODE) var_set_variable(expr->d.nodes.first->d.string_constant, first); free(first); free(second); break; #ifdef DEBUG default: printf("zwgc: internal error: attempt to evaluate the following non-expression:\n"); fflush(stdout); node_display(expr); printf("\n\n"); exit(2); #endif } return(result); }