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/* 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 <marc@athena.mit.edu>
*
* $Id$
*
* Copyright (c) 1989 by the Massachusetts Institute of Technology.
* For copying and distribution information, see the file
* "mit-copyright.h".
*/
#include <sysdep.h>
#if (!defined(lint) && !defined(SABER))
static const char rcsid_eval_c[] = "$Id$";
#endif
#include <zephyr/mit-copyright.h>
/****************************************************************************/
/* */
/* Code to evaluate an expression: */
/* */
/****************************************************************************/
#include <zephyr/zephyr.h>
#include "new_memory.h"
#include "node.h"
#include "eval.h"
#include "substitute.h"
#include "port.h"
#include "buffer.h"
#include "regexp.h"
#include "formatter.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(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(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(Node *expr)
{
int opcode = expr->opcode;
int bool_result = 0;
string first, second;
char *result = NULL;
string *text_ptr;
/*
* 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 STYLESTRIP_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 STYLESTRIP_OPCODE:
return(stylestrip(first));
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);
}
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