forth/src/fh_parse.c

#include <ctype.h>
#include <stdint.h>
#include <stddef.h>
#include "fh_print.h"
#include "fh_runtime.h"
#include "fh_error.h"
#include "fh_parse.h"

void fh_input_consume_matching(struct fh_thread_s *fh, chartest_t test, void* param) {
  char *rp = (char *) &fh->heap[INPUTBUF_ADDR + fh->inputptr];
  while (test(*rp, param)) {
    rp++;
    fh->inputptr++;
  }
}

void fh_input_consume_spaces(struct fh_thread_s *fh) {
  char *rp = (char *) &fh->heap[INPUTBUF_ADDR + fh->inputptr];
  while (isspace(*rp)) {
    rp++;
    fh->inputptr++;
  }
}

enum fh_error fh_input_read_delimited(struct fh_thread_s *fh, char **out, size_t *len, chartest_t test, void* param)
{
  char *rp = (char *) &fh->heap[INPUTBUF_ADDR + fh->inputptr];
  char *start = rp;
  while (1) {
    char c = *rp;
    if (test(c, param)) {
      if (rp == start) {
        LOGE("Expected a word!");
        return FH_ERR_SYNTAX;
      }
      *out = start;
      *len = rp - start;
      fh->inputptr++; // advance past the delimiter
      return FH_OK;
    }
    rp++;
    fh->inputptr++;
  }
}

static bool chartest_space_or_end(char c, void *param)
{
  (void)param;
  return isspace(c) || c == 0;
}

enum fh_error fh_input_read_word(struct fh_thread_s *fh, char **out, size_t *len) {
  return fh_input_read_delimited(fh, out, len, chartest_space_or_end, NULL);
}

enum fh_error fh_input_read_quotedstring(struct fh_thread_s *fh, bool escaped, char *outbuf, size_t capacity, size_t *out_len) {
  char *rp = (char *) &fh->heap[INPUTBUF_ADDR + fh->inputptr];
  bool next_escaped = false;
  size_t remains = capacity;
  size_t len = 0;
  int hexdigits = 0;
  uint32_t hex = 0;
  while (len < capacity) {
    char c = *rp;
    if (c == 0) {
      LOGE("Unterminated quoted string!");
      return FH_ERR_SYNTAX;
    }

    if (hexdigits) {
      hex <<= 4;
      if (isdigit(c)) {
        hex |= c - '0';
      } else if (c>='a' && c<='f') {
        hex |= c - 'a';
      } else if (c>='A' && c<='F') {
        hex |= c - 'A';
      } else {
        LOGE("Bad hex escape");
        return FH_ERR_SYNTAX;
      }
      hexdigits--;
      if (hexdigits == 0) {
        c = (char) hex;
        goto append;
      }
    }

    if (!escaped || !next_escaped) {
      if (c == '\"') {
        *outbuf = 0;
        *out_len = len;
        // advance past the quote
        fh->inputptr++;
        return FH_OK;
      }

      if (c == '\\') {
        next_escaped = true;
        goto skip;
      }
    } else {
      next_escaped = false;
      switch (c) {
        case 'a': c = 7; break;
        case 'b': c = 8; break;
        case 'e': c = 27; break;
        case 'f': c = 12; break;
        case 'l': c = 10; break;
        case 'm':
        case 'n':
          if (remains < 2) goto full;
          *outbuf++ = '\r';
          *outbuf++ = '\n';
          remains -= 2;
          len += 2;
          goto skip;
        case 'q': c = '"'; break;
        case 'r': c = '\r'; break;
        case 't': c = '\t'; break;
        case 'v': c = '\v'; break;
        case 'z': c = 0; break; // XXX this will cause problems!
        case 'x':
          hex = 0;
          hexdigits = 2;
          goto skip;
        default:;
          // just append normally
      }
    }

    append:
    *outbuf++ = c;
    len++;
    skip:
    rp++;
    fh->inputptr++;
  }

  full:
  LOGE("String too long!");
  return FH_ERR_SYNTAX;
}