src/apc/lexer.c

   1 /*!@file
   2   \brief   lexical analyzer implementation for APC
   3   \details this lexer scans a root directory given from the command line
   4            for subdirectories and files structured for the APC grammar.
   5   \author  Jordan Lavatai
   6   \date    Aug 2016
   7   ----------------------------------------------------------------------------*/
   8 //stdc
   9 #include <stdio.h>
  10 #include <string.h>
  11 #include <errno.h>
  12 //posix
  13 #include <unistd.h>
  14 #include <stdlib.h>
  15 //bison
  16 #include "fileparser.tab.h"
  17 #define TOKEN_BUF_SIZE 1024
  18 #define DIRP_STACK_SIZE 512
  19
  20 int lexer_init(void);
  21 int lexer(void);
  22
  23 static
  24 int lexer_scan(void);
  25
  26 static
  27 int  token_buf[TOKEN_BUF_SIZE], *tbp, *tbx;
  28 static
  29 DIR* dirp_stack[DIRP_STACK_SIZE], *dsp;
  30
  31 /* Initialize pointers */
  32 int
  33 lexer_init()
  34 { tbp = tbx = token_buf;
  35   dsp = dirp_stack;
  36   return 0;
  37 }
  38
  39 /* Returns a token identifier and sets yylval */
  40 int
  41 lexer()
  42 { if (lexer_scan() == 0)
  43     return 0;
  44   yylval = *tbp++;
  45   return *tbp++;
  46 }
  47
  48 /* Scanner
  49    Scans a filename from its alphabetically ordered list of file elements
  50    and tokenizes the result.  If the file list is empty, then the stack of
  51    directory elements will be popped and processed as they are encountered.
  52
  53    Returns the number of tokens generated.
  54 */
  55 #define MAX_ENTITIES 256
  56 static
  57 int lexer_scan()
  58 { static struct dirent* entity;
  59   static struct dirent* files[MAX_ENTITIES];
  60   static struct dirent* dirs = files + MAX_ENTITIES - 1;
  61   static int            num_files = 0;
  62   static int            num_dirs = 0;
  63
  64   //sort out files and directories, grow directories from bottom up
  65   while ((entity = readdir(dirp)) != NULL)
  66     { switch (entity->d_type)
  67         { case DT_LNK:
  68           case DT_REG:
  69             files[num_files++] = entity;
  70             break;
  71           case DT_DIR:
  72             *(dirs - num_dirs++) = entity;
  73             break;
  74           case DT_UNKNOWN:
  75           default:
  76             printf("Ignoring unknown file: %s\n", entity->d_name);
  77             break;
  78         }
  79     }
  80   if (errno)
  81     perror("readdir");
  82   qsort(&files[0], num_files, sizeof struct dirent*, qalpha);
  83   num_ents = scandirat(dirfd, ".", &namelist, scanfilter, scancompar);
  84   if (num_ents < 0)
  85     { perror("scandirat");
  86       return -1;
  87     }
  88   //process files
  89
  90   //recurse into directories
  91
  92 }