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prepifelse.cpp
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C/C++ Source or Header
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2002-02-08
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442 lines
/****************************************************************************
*
* wxWindows HTML Applet Package
*
* Copyright (C) 1991-2001 SciTech Software, Inc.
* All rights reserved.
*
* ========================================================================
*
* The contents of this file are subject to the wxWindows License
* Version 3.0 (the "License"); you may not use this file except in
* compliance with the License. You may obtain a copy of the License at
* http://www.wxwindows.org/licence3.txt
*
* Software distributed under the License is distributed on an
* "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
* implied. See the License for the specific language governing
* rights and limitations under the License.
*
* ========================================================================
*
* Language: ANSI C++
* Environment: Any
*
* Description: This file is the implementation of the Preprocessor object
* for parsing the <!--#if directive
*
****************************************************************************/
// Include private headers
#include "wx/applet/prepifelse.h"
#include "wx/applet/ifelsevar.h"
#include "wx/applet/echovar.h"
#include "wx/string.h"
// Force link macro
#include "wx/html/forcelnk.h"
// wxWindows
#include "wx/msgdlg.h"
/*----------------------------- Implementation ----------------------------*/
/* {SECRET} */
/****************************************************************************
REMARKS:
None of the Reverse Find functions in wxWindows appear to work in a way that
can be used by our code. This includes the libstr rfind implementations which
do not correctly pass the given return value.
****************************************************************************/
int ReverseFind(
const wxString &tstr,
const wxString &str,
int start = -1)
{
wxASSERT( str.GetStringData()->IsValid() );
// TODO could be made much quicker than that
int p = tstr.Len()-str.Len()-1;
int p2 = start-str.Len();
// if the user supplied a valid start point, use it
if (start != -1 && p > p2) p = p2;
while ( p >= 0 ) {
if ( wxStrncmp(tstr.c_str() + p, str.c_str(), str.Len()) == 0 )
return p;
p--;
}
return -1;
}
/* {SECRET} */
/****************************************************************************
REMARKS:
tells if a character is a letter.
replace this when wxWindows gets regex library. (without strange licensing
restrictions)
****************************************************************************/
bool IsLetter(
char c, bool acceptspace = false)
{
if (acceptspace && (c == ' ')) return true;
if (c >= '0' && c <= '9') return true;
return ((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || c == '_' || c == '\"' || c == '\'' );
}
#define IsQuote(c) (c == '\'' || c == '\"')
/* {SECRET} */
/****************************************************************************
REMARKS:
tells if a character is a letter.
replace this when wxWindows gets regex library. (without strange licensing
restrictions)
****************************************************************************/
wxString GetEquals(
wxString var,
wxString value)
{
if (!wxEchoVariable::Exists(var)) {
// TODO: when we implement the set variable, check for a set variable as well
#ifdef CHECKED
wxMessageBox(wxString("wxHTML #if\\else error: Variable ") + var + wxString(" not found."),"Error",wxICON_ERROR);
#endif
return wxString("0"); // false
}
wxString tmp = wxEchoVariable::GetValue(var);
if (IsQuote( value.GetChar(0) ))
value = value.Mid(1);
if (IsQuote(value.GetChar(value.Length()-1)))
value = value.Mid(0,value.Length()-1);
if (tmp.CmpNoCase(value) == 0) return wxString("1");
return wxString("0");
}
/****************************************************************************
PARAMETERS:
str - text of #if statement
RETURNS:
true or false depending on how it evaluated
REMARKS:
TODO: rewrite this whole thing using regular expressions when they are done.
SEE ALSO:
wxIfElseVariable
****************************************************************************/
bool ParseIfStatementValue(
wxString &str)
{
// Find out if the tag has parenthesis
// recursive to parse the text within the parenthesis,
// replacing the text with 1 or 0, (hardcoded true or false)
int b;
while ((b = str.Find('(')) != -1) {
int e;
// Find the matching parenthesis
int nextbeg, nextend;
int parencount = 1, min = b+1;
do {
nextbeg = str.find('(', min);
nextend = str.find(')', min);
if (nextbeg < nextend && nextbeg != wxString::npos) {
parencount++;
min = nextbeg+1;
}
else {
parencount--;
min = nextend+1;
}
if (nextend == wxString::npos) {
#ifdef CHECKED
wxMessageBox("wxHTML #if\\else error: Unmatched parenthesis in #if expression.","Error",wxICON_ERROR);
#endif
return true;
}
// once parencount reaches 0 again we have found our matchin )
} while (parencount > 0);
e = nextend;
// Extract the expression from the parenthesis block and recurse
// to solve it.
wxString tag;
tag = str.Mid(b+1, e-b-1);
bool val = ParseIfStatementValue(tag);
// Add extra spaces just in case of NOT(VAL)
if (val) str = str.Mid(0, b) + " 1" + str.Mid(e+1);
else str = str.Mid(0, b) + " 0" + str.Mid(e+1);
}
// Remove spaces from left and right
str.Trim(false);
str.Trim(true);
// Convert text method of operators "AND" and "OR" to c style
// this makes only one special case necessary for each later on
str.Replace(" AND ", "&&");
str.Replace(" OR ", "||");
str.Replace(" EQUALS ", "==");
// Check for equals statements
// == statements are special because they are evaluated as a single block
int equ;
equ = str.find("==");
while (equ != wxString::npos) {
int begin, end;
int begin2, end2; // ends of words
begin = equ-1;
end = equ+2;
// remove spaces, find extents
while (end < str.Length() && str.GetChar(end) == ' ')
end++;
while (begin >= 0 && str.GetChar(begin) == ' ')
begin--;
end2 = end;
begin2 = begin;
if (str.GetChar(end2) == '\'' || str.GetChar(end2) == '\"') {
end2++;
while (end2 < str.Length() && str.GetChar(end2) != '\'' && str.GetChar(end2) != '\"' )
end2++;
end2++;
}
else {
while (end2 < str.Length() && IsLetter(str.GetChar(end2)))
end2++;
}
while (begin >= 0 && IsLetter(str.GetChar(begin)))
begin--;
if (begin < 0) begin = 0;
else begin++;
if (end2 >= str.Length()) end2 = str.Length();
wxString tmpeq = GetEquals(str.Mid(begin, begin2-begin+1), str.Mid(end, end2-end));
str = str.Mid(0, begin) + wxString(" ") + tmpeq + wxString(" ") +
str.Mid(end2);
equ = str.find("==");
// Remove spaces from left and right
str.Trim(false);
str.Trim(true);
}
// We use ReverseFind so that the whole left expression gets evaluated agains
// the right single item, creating a left -> right evaluation
// Search for || operators, recurse to solve (so we don't have to handle special cases here)
int and, or;
and = ReverseFind(str, "&&");
or = ReverseFind(str, "||");
if ( (and != -1) || (or != -1) ) {
wxString tag1, tag2;
// handle the rightmost first to force left->right evaluation
if ( (and > or) ) {
return (
ParseIfStatementValue(tag2 = str.Mid(and+2)) &&
ParseIfStatementValue(tag1 = str.Mid(0, and)) );
}
else {
return (
ParseIfStatementValue(tag2 = str.Mid(or+2)) ||
ParseIfStatementValue(tag1 = str.Mid(0, or)) );
}
}
// By the time we get to this place in the function we are guarenteed to have a single
// variable operation, perhaps with a NOT or ! operator
bool notval = false;
// search for a NOT or ! operator
if (str.Mid(0, 1) == "!") {
str.Remove(0, 1);
str.Trim(false); // trim spaces from left
notval = true;
}
else if (str.Mid(0,4).CmpNoCase("NOT ") == 0) {
str.Remove(0, 4);
str.Trim(false); // trim any extra spaces from left
notval = true;
}
// now all we have left is the name of the class or a hardcoded 0 or 1
if (str == "") {
#ifdef CHECKED
wxMessageBox("wxHTML #if\\else error: Empty expression in #if\\#elif statement.","Error",wxICON_ERROR);
#endif
return true;
}
// check for hardcoded 0 and 1 cases, (these are used by parenthesis catcher)
// this just decomplicates the recursion algorithm
if (str == "0") return notval;
if (str == "1") return !notval;
// Grab the value from the variable class identified by cname
bool value = wxIfElseVariable::GetValue(str);
if (notval) value = !value;
return value;
}
/****************************************************************************
PARAMETERS:
text - HTML to process for if/else blocks
RETURNS:
The string containing the processed HTML
REMARKS:
This function replaces #if, #else, #elif, and #endif directives with the text
contained within the blocks, dependant on the value of the given boolean
variable. The variable is created by making a sub class of wxIfElseVariable.
Dynamic class construction is used at run time internally to create an instance
of this class and access the value of the variable.
SEE ALSO:
wxIfElseVariable
****************************************************************************/
wxString wxIfElsePrep::Process(
const wxString& text) const
{
int b;
char ft[] = "<!--#if ";
char ftend[] = "<!--#endif-->";
char ftelse[] = "<!--#else-->";
char ftnot[] = "<!--#if not ";
char ftnot2[] = "<!--#if !";
char ftelif[] = "<!--#elif ";
// make a copy so we can replace text as we go without affecting the original
wxString output = text;
// Avoid duplication of our parsing code by turning any #elif blocks into appropriate
// else/if blocks
while ((b = ReverseFind(output.Lower(), ftelif)) != -1) {
int e;
// Replace beginning of block
e = output.find("-->", b + strlen(ftelif));
if (e == wxString::npos) {
#ifdef CHECKED
wxMessageBox("wxHTML #elif error: Premature end of file while parsing #elif.","Error",wxICON_ERROR);
#endif
break;
}
// Convert to lower case so find is easy, grab everything after #elif tag
wxString remains = (output.Mid(e+strlen("-->"))).Lower();
// find matching else or endif
int nextif, nextendif;
int ifcount = 1, min = 0;
do {
nextif = remains.find(ft, min);
nextendif = remains.find(ftend, min);
if (nextif < nextendif && nextif != wxString::npos) {
ifcount++;
min = nextif+1;
}
else {
ifcount--;
min = nextendif+1;
}
if (nextendif == wxString::npos) {
#ifdef CHECKED
wxMessageBox("wxHTML #elif error: Premature end of file before finding #endif.","Error",wxICON_ERROR);
#endif
break;
}
// once ifcount reaches 0 again we have found our matchin #endif
} while (ifcount > 0);
// If it couldn't be found die gracefully
if (nextendif == wxString::npos) {
// We already displayed a message, just break all the way out
break;
}
int elifsize = e - (b + strlen(ftelif)) + strlen("-->");
// Create the #if/else block, removing the #elif code
output = output.Mid(0, b) +
wxString(wxString(ftelse)+wxString(ft)) +
output.Mid(b+strlen(ftelif), elifsize+nextendif) +
wxString(ftend) +
output.Mid(b+strlen(ftelif)+elifsize+nextendif);
}
// Parse out the if else blocks themselves
while ((b = ReverseFind(output.Lower(), ft)) != -1) {
// Loop until every #if directive is found
// We search from the end of the string so that #if statements will properly recurse
// and we avoid the hassle of matching statements with the correct <!--#endif-->
bool notval = false;
int off = 0;
int end;
wxString usecode, code;
wxString cname;
wxString tag;
bool value;
code = wxString("");
// grab the tag and get the name of the variable
end = (output.Mid(b)).Find("-->");
if (end == -1) {
#ifdef CHECKED
wxMessageBox("wxHTML #if error: Premature end of file while parsing #if.","Error",wxICON_ERROR);
#endif
break;
}
end += 3;
// remove the <!--#if and --> sections from the tag before passing it on to be parsed
tag = output.Mid(b+strlen(ft), end-strlen(ft)-3);
output.Remove(b, end);
value = ParseIfStatementValue(tag);
// Find the end of the tag (<!--#endif-->) and copy it all into the variable code
end = ((output.Mid(b)).Lower()).Find(ftend);
if (end == -1) {
#ifdef CHECKED
wxMessageBox("wxHTML #if error: Premature end of file while searching for matching #endif.","Error",wxICON_ERROR);
#endif
break;
}
code = output.Mid(b, end);
output.Remove(b, end+strlen(ftend)); // remove the entire #if block from original document
// Find out if there is an else statement
end = (code.Lower()).Find(ftelse);
if (end != -1) {
if (!value) {
// Use the else statement
usecode = code.Mid(end+strlen(ftelse));
}
else {
// Use statement before #else
usecode = code.Mid(0, end);
}
}
else if (value) {
// There is no #else statement
usecode = code;
}
if (usecode != wxString(""))
output = (output.Mid(0,b) + usecode + output.Mid(b));
}
return output;
}
FORCE_LINK(ifelsevar)