/*
  Copyright 2002-2003 John Plevyak, All Rights Reserved
*/

#include "d.h"

int
scan_buffer(d_loc_t *loc, D_State *parse_state, ShiftResult *results) {
  char *s = loc->s, *scol = 0;
  int col = loc->col, collast = col, line = loc->line;
  int nresults = 0, i, j;
  D_Shift **shift = NULL;

  if (parse_state->scan_kind != D_SCAN_LONGEST) {
    /* all matches */
    SB_uint8 *st = (SB_uint8*)parse_state->scanner_table;
    SB_trans_uint8 *tst = (SB_trans_uint8*)parse_state->transition_table;
    uint8 state = 0, last = state;
    uint8 c;
    uint32 sb, so;
    c = (uint8)*s++;
    while ((state = st[state].scanner_block[(sb = (c >> SCANNER_BLOCK_SHIFT))]
	    [(so = c & SCANNER_BLOCK_MASK)]))
    {
      state -= 1;
      if (st[state].shift) {
	last = state;
	loc->s = s; collast = col; loc->line = line;
	shift = parse_state->accepts_diff[tst[state].scanner_block[sb][so]];
	for (; *shift; shift++) {
	  results[nresults].loc = *loc;
	  results[nresults++].shift = *shift;
	}
      }
      if (c == '\n') { line++; col = 0; scol = s; } else col++;
      c = (uint8)*s++;
    }
    loc->col = scol ? s - scol : -1;
    shift = st[last].shift;
    if (shift) {
      loc->line = line;
      for (; *shift; shift++) {
	results[nresults].loc = *loc;
	results[nresults++].shift = *shift;
      }
    }
    if (nresults && parse_state->scan_kind == D_SCAN_MIXED) {
      char *end = results[nresults-1].loc.s;
      int longest = 0;
      for (i = nresults - 1; i >= 0; i--) {
	if (results[i].shift->shift_kind == D_SCAN_LONGEST)
	  longest = 1;
	if (results[i].loc.s < end)
	  break;
      }
      if (!longest) {
	/* only keep non-longest */
	for (j = i; j >= 0; j--)
	  if (results[j].shift->shift_kind != D_SCAN_LONGEST) {
	    if (i != j) 
	      results[i] = results[j];
	    i--;
	  }
	nresults = nresults - i - 1;
	if (i != -1)
	  memmove(&results[0], &results[i + 1], nresults * sizeof(results[0]));
      } else {
	/* keep only 'longest' */
	i = 0;
	for (j = 0; j < nresults; j++)
	  if (results[j].loc.s == end) {
	    if (i != j)
	      results[i] = results[j];
	    i++;
	  }
	nresults = i;
      }
    }
    return nresults;
  } else {
    /* longest match only */
    switch (parse_state->scanner_size) {
      case 1: {
	SB_uint8 *st = (SB_uint8*)parse_state->scanner_table;
	uint8 state = 0, last = state;
	uint8 c;
	c = (uint8)*s++;
	while ((state = st[state].scanner_block[c >> SCANNER_BLOCK_SHIFT]
		[c & SCANNER_BLOCK_MASK]))
	{
	  state -= 1;
	  if (st[state].shift) {
	    last = state;
	    loc->s = s; collast = col; loc->line = line;
	  }
	  if (c == '\n') { line++; col = 0; scol = s; } else col++;
	  c = (uint8)*s++;
	}
	shift = st[last].shift;
	break;
      }
      case 2: {
	SB_uint16 *st = (SB_uint16*)parse_state->scanner_table;
	uint16 state = 0, last = state;
	uint8 c;
	c = (uint8)*s++;
	while ((state = st[state].scanner_block[c >> SCANNER_BLOCK_SHIFT]
		[c & SCANNER_BLOCK_MASK]))
	{
	  state -= 1;
	  if (st[state].shift) {
	    last = state;
	    loc->s = s; collast = col; loc->line = line;
	  }
	  if (c == '\n') { line++; col = 0; scol = s; } else col++;
	  c = (uint8)*s++;
	}
	shift = st[last].shift;
	break;
      }
      case 4: {
	SB_uint32 *st = (SB_uint32*)parse_state->scanner_table;
	uint32 state = 0, last = state;
	uint8 c;
	c = (uint8)*s++;
	while ((state = st[state].scanner_block[c >> SCANNER_BLOCK_SHIFT]
		[c & SCANNER_BLOCK_MASK]))
	{
	  state -= 1;
	  if (st[state].shift) {
	    last = state;
	    loc->s = s; collast = col; loc->line = line;
	  }
	  if (c == '\n') { line++; col = 0; scol = s; } else col++;
	  c = (uint8)*s++;
	}
	shift = st[last].shift;
	break;
      }
    }
    loc->col = scol ? s - scol : -1;
    if (shift) {
      loc->line = line;
      for (; *shift; shift++) {
	results[nresults].loc = *loc;
	results[nresults++].shift = *shift;
      }
    }
    return nresults;
  }
}