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/*
*
* Begin of Skeleton
*
*/
/* ****************************************************************
C Skeleton Parser for matrix tables
This is not a sample program, but rather the parser skeleton
to be included in the generated code.
Modify at your own risk.
Copyright (c), 1985-2012 Jaime Garza
***************************************************************** */
/* Define this as a matrix parser */
#define STX_TABULAR
/* Force an error */
#ifndef STX_ERROR
#define STX_ERROR {ErrorFlag = -1; return FALSE;}
#endif
/* Global variables */
TSTACK StxValue; /* Scanner OUT value. Intended for scanner writer */
char StxChar; /* The curent character */
int sStxStack[STACK_DEPTH]; /* State stack. Internal use */
unsigned long int StxSym; /* Actual scanner symbol. Internal usage */
int StxState; /* Current automaton state. Internal usage */
int StxErrors; /* Counts the number of errors. User can read */
int StxErrorFlag; /* Recuperation machinery state. Internal usage */
#define ERROR_FAIL 0
#define ERROR_RE_ATTEMPT 1
/* These functions must be provided by the user */
unsigned long int StxLexer();
int StxError(int StxState, int StxSym, int pStxStack, char * message);
#ifdef DEBUG
char * StxToString(TSTACK value);
#endif
/*
This routine maps a state and a token to a new state on the action table
*/
int StxAction(int state, int symbol)
{
int index = StxGetTokenIndex(symbol);
return StxParsingTable[state][index];
}
/*
This routine maps a origin state to a destination state
using the symbol position
*/
int StxGoto(int state, int symbol)
{
int index = symbol;
return StxParsingTable[state][index];
}
/*
This routine prints the contents of the parsing stack
*/
#ifdef DEBUG
void StxPrintStack()
{
int i;
printf("Stack pointer = %d\n", pStxStack);
printf("States: [");
for(i=0;i<=pStxStack;i++)
printf(" %d", sStxStack[i]);
printf("]<--Top of Stack (%d)\n", pStxStack);
printf("Values: [");
for(i=0;i<=pStxStack;i++)
printf(" %s", StxToString(StxStack[i]));
printf("]<--Top of Stack (%d)\n", pStxStack);
}
#endif
char * StxErrorMessage() {
int msgIndex = StxParsingError[StxState];
if (msgIndex >= 0) {
return StxErrorTable[msgIndex];
} else {
return "Syntax error";
}
}
/*
Does a shift operation. Puts a new state on the top of the stack
*/
int StxShift(int sym, int state)
{
if(pStxStack >= STACK_DEPTH-1)
return 0;
sStxStack[++pStxStack] = state;
StxStack[pStxStack] = StxValue;
StxState = state;
#ifdef DEBUG
printf("Shift to %d with %d\n", StxState, sym);
StxPrintStack();
#endif
return 1;
}
/*
Recognizes a rule an removes all its elements from the stack
*/
int StxReduce(int sym, int rule)
{
#ifdef DEBUG
printf("Reduce on rule %d with symbol %d\n", rule, sym);
#endif
if(!StxCode(rule))
return 0;
pStxStack -= StxGrammarTable[rule].reductions;
sStxStack[pStxStack+1] =
StxGoto(sStxStack[pStxStack], StxGrammarTable[rule].symbol);
StxState = sStxStack[++pStxStack];
#ifdef DEBUG
StxPrintStack();
#endif
return 1;
}
/*
Recover from a syntax error removing stack states/symbols, and removing
input tokens. The array StxRecover contains the tokens that bound
the error
*/
int StxRecover(void)
{
int i, acc;
switch(StxErrorFlag){
case 0: /* 1st error */
if(!StxError(StxState, StxSym, pStxStack, StxErrorMessage()))
return 0;
StxErrors++;
/* goes into 1 and 2 */
case 1:
case 2: /* three attempts are made before dropping the current token */
StxErrorFlag = 3; /* Remove token */
while(pStxStack >= 0){
/* Look if the state on the stack's top has a transition with one of
the recovering elements in StxRecoverTable */
for(i=0; i 0)
/* valid shift */
return StxShift(StxRecoverTable[i], acc);
#ifdef DEBUG
printf("Recuperate removing state %d and go to state %d\n",
StxState, sStxStack[pStxStack-1]);
#endif
StxState = sStxStack[--pStxStack];
}
pStxStack = 0;
return 0;
case 3: /* I need to drop the current token */
#ifdef DEBUG
printf("Recuperate removing symbol %d\n", StxSym);
#endif
if(StxSym == 0) /* End of input string */
return 0;
StxSym = StxLexer();
return 1;
}
}
/*
Initialize the scanner
*/
void StxInit() {
pStxStack = 0;
sStxStack[0] = 0;
StxState = 0;
}
/*
Main parser routine, uses Shift, Reduce and Recover
*/
int StxParse(int symbol, TSTACK value)
{
int action;
StxSym = StxGetTokenIndex(symbol);
StxValue = value;
#ifdef DEBUG
printf("Starting to parse symbol %d (%d)\n", symbol, StxSym);
StxPrintStack();
#endif
while(1 == 1) { // forever with break and return below
action = StxAction(StxState, symbol);
#ifdef DEBUG
printf("Action: %d\n", action);
#endif
if(action == ACCEPT) {
#ifdef DEBUG
printf("Program Accepted\n");
#endif
return ACCEPTED;
}
if(action > 0) {
if(StxShift(StxSym, action) == 0) {
return INTERNAL_ERROR;
}
return SHIFTED;
} else if(action < 0) {
if(StxReduce(StxSym, -action) == 0) {
return INTERNAL_ERROR;
}
} else if(action == 0) {
return PARSING_ERROR;
}
}
}
/*
give me the available actions that can be taken. I am also returning reduces.
*/
int * StxValidTokens(int * count) {
int c = 0;
int i;
for (i = 0; i < TOKENS; i++) {
if(StxParsingTable[StxState][i] != 0) {
c ++;
}
}
int * actions = malloc(c * sizeof(int));
int index = 0;
#ifdef DEBUG
printf ("Valid actions:[");
#endif
for(i=0; i < TOKENS; i++) {
if (StxParsingTable[StxState][i] != 0) {
#ifdef DEBUG
if (index > 0) printf(", ");
printf("%d", StxTokenDefs[i].token);
#endif
actions[index++] = StxTokenDefs[i].token;
}
}
#ifdef DEBUG
printf ("]\n");
#endif
*count = c;
return actions;
}
TSTACK StxGetResult() {
return StxStack[pStxStack];
}
/*
* returns the name of a token, given the token number
*/
char * StxGetTokenName(int token) {
int i;
for (i = 0; i < TOKENS; i++) {
if (StxTokenDefs[i].token == token) {
return StxTokenDefs[i].name;
}
}
return "UNKNOWN TOKEN";
}
/*
* Find the index of a token
*/
int StxGetTokenIndex(int token) {
int i;
for (i = 0; i < TOKENS; i++) {
if (StxTokenDefs[i].token == token) {
return i;
}
}
return -1;
}
/* End of parser */
