bool GrammarRead(Grammar *grammar, const char *fileName)
{
// Read the file.
grammar->fileName = fileName;
FILE *srcFile = fopen(fileName, "r");
if (srcFile == NULL)
{
AllocSprintf(&grammar->errMsg, "can't open '%s'", fileName);
return false;
}
// Go through it line by line.
grammar->lineNo = 1;
char line[4096];
while (fgets(line, sizeof(line), srcFile))
{
// Remove comments.
char *commentPos = strstr(line, "//");
if (commentPos != NULL)
{
*commentPos = 0;
}
// Remove trailing whitespace.
StringStripEnd(line);
// Skip empty lines.
if (line[0] != 0)
{
// Is it a definition line?
if (isalpha(line[0]))
{
// Parse a definition.
if (!GrammarParseDefinition(grammar, line))
goto grErrExit;
}
else if (isspace(line[0]))
{
// Parse an option.
if (!GrammarParseOption(grammar, line))
goto grErrExit;
}
else
{
// Unexpected character.
AllocSprintf(&grammar->errMsg, "unexpected character in %s line %d: '%s'", fileName, grammar->lineNo, line);
goto grErrExit;
}
}
grammar->lineNo++;
}
return true;
grErrExit:
fclose(srcFile);
return false;
}
bool GrammarParseCharSet(Grammar *grammar, GrammarItem *item, char **pos)
{
// A bitset of allowed characters.
uint8_t charSet[MAX_CHARSET / 8];
bool positiveSet = true;
// Skip the leading brace character.
if (**pos == '{')
{
(*pos)++;
}
// Is this a positive or negative set?
if (**pos == '^')
{
positiveSet = false;
(*pos)++;
memset(charSet, 0xff, sizeof(charSet));
}
else
{
positiveSet = true;
memset(charSet, 0, sizeof(charSet));
}
// Add/remove each of the specified characters.
int ch;
while (**pos != '}' && **pos != 0 && GrammarParseCharacter(pos, &ch))
{
if (ch < MAX_CHARSET)
{
if (positiveSet)
{
// Add it to the bitset.
charSet[ch/8] = charSet[ch/8] | (1<<(ch%8));
}
else
{
// Remove it from the bitset.
charSet[ch/8] = charSet[ch/8] & ~(1<<(ch%8));
}
}
}
// Did the character set finish suitably?
if (**pos != '}')
{
AllocSprintf(&grammar->errMsg, "character set is missing a closing brace in line %d\n", grammar->lineNo);
return false;
}
(*pos)++;
// Copy the result to the item.
item->charSet = calloc(MAX_CHARSET / 8, sizeof(uint8_t));
memcpy(item->charSet, charSet, MAX_CHARSET/8);
return true;
}
bool GrammarParseOption(Grammar *grammar, char *line)
{
char *pos = line;
SkipWhitespace(&pos);
// Create an option node.
GrammarOption *opt = calloc(1, sizeof(*opt));
if (opt == NULL)
{
AllocSprintf(&grammar->errMsg, "out of memory");
return false;
}
// Add it to the end of the list.
GrammarDefinition *def = grammar->lastDef;
if (def == NULL)
{
AllocSprintf(&grammar->errMsg, "option before definition, line %d", grammar->lineNo);
free(opt);
return false;
}
if (def->firstOption == NULL)
{
def->firstOption = opt;
def->lastOption = opt;
}
else
{
def->lastOption->nextOption = opt;
def->lastOption = opt;
}
opt->nextOption = NULL;
opt->firstItem = NULL;
opt->lastItem = NULL;
// Parse the items.
bool ok = false;
while (GrammarParseItem(grammar, opt, &pos, &ok))
{
}
return ok;
}
bool GrammarParseDefinition(Grammar *grammar, char *line)
{
// Create a definition node.
GrammarDefinition *def = calloc(1, sizeof(*def));
if (def == NULL)
{
AllocSprintf(&grammar->errMsg, "out of memory");
return false;
}
// Add it to the end of the list.
if (grammar->firstDef == NULL)
{
grammar->firstDef = def;
grammar->lastDef = def;
}
else
{
grammar->lastDef->nextDefinition = def;
grammar->lastDef = def;
}
def->nextDefinition = NULL;
def->firstOption = NULL;
def->lastOption = NULL;
char *pos = line;
def->name = GrammarParseIdentifier(&pos);
// There should only be a colon after the identifier.
SkipWhitespace(&pos);
if (*pos != ':')
{
AllocSprintf(&grammar->errMsg, "colon expected in definition, line %d", grammar->lineNo);
return false;
}
pos++;
if (*pos != 0)
{
AllocSprintf(&grammar->errMsg, "unexpected text after definition, line %d", grammar->lineNo);
return false;
}
return true;
}
bool GrammarRead(Grammar *grammar, const char *fileName)
{
// Read the file.
grammar->fileName = fileName;
if (!ReadFile(&grammar->src, &grammar->errMsg, fileName))
return false;
// Go through it line by line.
grammar->lineNo = 1;
char *line;
char *nextLine = grammar->src;
while (ReadLine(&line, &nextLine))
{
// Remove comments.
char *commentPos = strstr(line, "//");
if (commentPos != NULL)
{
*commentPos = 0;
}
// Remove trailing whitespace.
StringStripEnd(line);
// Skip empty lines.
if (line[0] != 0)
{
// Is it a definition line?
if (isalnum(line[0]))
{
// Parse a definition.
if (!GrammarParseDefinition(grammar, line))
return false;
}
else if (isspace(line[0]))
{
// Parse an option.
if (!GrammarParseOption(grammar, line))
return false;
}
else
{
// Unexpected character.
AllocSprintf(&grammar->errMsg, "unexpected character in %s line %d: '%s'", fileName, grammar->lineNo, line);
return false;
}
}
grammar->lineNo++;
}
return true;
}
bool GrammarParseString(Grammar *grammar, GrammarItem *item, char **pos)
{
// Skip the leading quote character.
if (**pos == '\'')
{
(*pos)++;
}
// Gather characters until we reach a closing single quote or the end of the string.
int ch;
int i = 0;
char str[MAX_STRING+1];
while (GrammarParseCharacter(pos, &ch) && i < MAX_STRING)
{
str[i] = ch;
i++;
}
// Null terminate the string.
str[i] = 0;
// Did the string finish suitably?
if (**pos == '\'')
{
(*pos)++;
item->token = strdup(str);
return true;
}
else if (**pos == 0)
{
AllocSprintf(&grammar->errMsg, "string is missing a closing quote in line %d\n", grammar->lineNo);
return false;
}
AllocSprintf(&grammar->errMsg, "string terminates strangely in line %d\n", grammar->lineNo);
return false;
}
bool GrammarParseItem(Grammar *grammar, char *str)
{
AllocSprintf(&grammar->errMsg, "unimplemented");
return false;
}
bool GrammarParseOption(Grammar *grammar, char *line)
{
AllocSprintf(&grammar->errMsg, "unimplemented");
return false;
}
bool GrammarParseItem(Grammar *grammar, GrammarOption *option, char **pos, bool *ok)
{
*ok = true;
// Are we at the end of the line?
SkipWhitespace(pos);
if (**pos == 0)
{
// There are no more items.
return false;
}
// Create an item node.
GrammarItem *item = calloc(1, sizeof(*item));
if (item == NULL)
{
AllocSprintf(&grammar->errMsg, "out of memory");
return false;
}
// Add it to the end of the list.
if (option->firstItem == NULL)
{
option->firstItem = item;
option->lastItem = item;
}
else
{
option->lastItem->nextItem = item;
option->lastItem = item;
}
item->nextItem = NULL;
item->repeated = false;
item->definitionName = NULL;
item->token = NULL;
item->charSet = NULL;
// Is it repeated?
bool repeated = false;
char ch = **pos;
if (ch == '[')
{
repeated = true;
(*pos)++;
}
// What kind of token is next?
switch (ch)
{
case 0:
AllocSprintf(&grammar->errMsg, "missing item after '[' in line %d\n", grammar->lineNo);
*ok = false;
break;
case '\'':
*ok = GrammarParseString(grammar, item, pos);
break;
case '{':
*ok = GrammarParseCharSet(grammar, item, pos);
break;
default:
if (isalpha(ch))
{
// Parse a definition name.
item->definitionName = GrammarParseIdentifier(pos);
}
else
{
// It's something unknown.
AllocSprintf(&grammar->errMsg, "unknown character in line %d\n", grammar->lineNo);
*ok = false;
}
break;
}
// If it was repeated, make sure we have a closing square bracket.
if (repeated)
{
if (**pos != ']')
{
AllocSprintf(&grammar->errMsg, "expected closing ']' after repeated term in line %d\n", grammar->lineNo);
*ok = false;
}
item->repeated = true;
}
// If we're failing out deallocate the item.
if (!*ok)
{
free(item);
return false;
}
return true;
}
