2 \brief lexical analyzer implementation for APC
3 \details The lexer manages two FIFO stacks. One for maintaining tokens, the
4 other for maintaining a list of files to be scanned. During
5 execution, the lexer will return a token from its token queue if any
6 are present. If not, the lexer will will pop an element from its
7 file queue to 'scanner' to be tokenized. If the file queue is empty,
8 the lexer will instead call 'parsedir' to traverse the directory tree
9 and tokenize the results. If 'parsedir' does not generate any new
11 \author Jordan Lavatai
13 ----------------------------------------------------------------------------*/
21 #include <limits.h> //realpath, NAME_MAX, PATH_MAX
24 #include "parser.tab.h"
26 #define DE_STACKSIZE 1024
29 #define TK_STACKSIZE 1024
34 int lexer_lexfile(const char*);
35 void lexer_pushtok(int, YYSTYPE
);
36 char const* lexer_get_current_filepath(void);
37 struct dirent
* lexer_direntpa
[DE_STACKSIZE
], **lexer_direntpp
;
40 int lexer_lex(const char*);
42 int scanner_init(void);
46 int dredge_current_depth(void);
50 char const* current_filename
;
53 { YYSTYPE lval
; //token val
54 int tok_t
; //token type
55 } token_stack
[TK_STACKSIZE
], *tsp
, *tsx
;
57 /* Directory Entity Array/Stack
58 Simple array for keeping track of dirents yet to be processed by the scanner.
59 If this list is empty and there are no tokens, the lexer is done.
60 This array is populated by the scanner as an array, and popped locally by the
63 #define DE_STACK (lexer_direntpa)
64 #define DE_STACKP (lexer_direntpp)
65 #define DE_LEN() (DE_STACKP - DE_STACK)
66 #define DE_INIT() (DE_STACKP = DE_STACK)
67 #define DE_POP() (*--DE_STACKP)
70 This is a FIFO stack whose pointers are a union of either a pointer to an
71 integer, or a pointer to two integers (a struct tok). This way, integers may
72 be added or removed from the stack either singularly (IPUSH/IPOP), or as a
73 full token of two integers (PUSH/POP).
74 An alignment error will occur if IPOP or IPUSH are used a non-even number of
77 #define TK_STACK (token_stack)
78 #define TK_STACKP (tsp)
79 #define TK_STACKX (tsx)
80 #define TK_LEN() (TK_STACKX - TK_STACKP)
81 #define TK_INIT() (TK_STACKP = TK_STACKX = TK_STACK)
82 #define TK_POP() (*TK_STACKP++)
83 #define TK_PUSH(T,L) (*TK_STACKX++ = (struct tok){L,T})
86 The initializer returns boolean true if an error occurs, which may be handled
93 return scanner_init();
97 If the token buffer is empty, 'lexer' will initialize the token buffer and
98 call 'lexer_scandir'. If SCAN_ERROR is returned, an error is printed
99 before sending a null return to bison. If 0 tokens are generated, the error
100 printing is skipped. In all other cases, 'yylval' is set, and the token's
101 integer representation is returned.
105 #define SCAN_ERROR -1
106 #define TK_EMPTY (TK_STACKP == TK_STACKX)
109 fprintf(stderr,__VA_ARGS__); \
115 while (DE_LEN() > 0) //lex any directory entries in our stack
116 if (lexer_lexfile(DE_POP()->d_name
) == 0)
117 FAIL("Lexer failed to tokenize [%s]\n",(*DE_STACKP
)->d_name
);
118 if (TK_EMPTY
) //if there are no tokens,
119 { TK_INIT(); //initialize the token stack back to 0
121 { case SCAN_ERROR
: //if an error occurred,
122 FAIL("Scanner error\n");
123 case 0: //if the the scanner finds no dirents,
124 goto done
; //then we are done
125 default: //if we found some elements to scan,
126 goto start
; //start over and lex them
139 This receiver takes a struct tok and pushes it to the FIFO stack.
142 #define $($)#$ //stringifier
143 #define ERR_TK "Fatal: Generated over " $(TK_STACKSIZE) " tokens in one pass."
144 ( int tok
, YYSTYPE lval
)
145 { if (TK_LEN() >= TK_STACKSIZE
)
146 { fprintf(stderr
, ERR_TK
);
152 /* Lexical analysis of a file
153 Strips a filename to its base name, then sends it to lexer_lex
156 #define HIDDEN_WARNING "%s is hidden and will not be parsed!\n", filename
157 ( const char *filename
159 { static char fname
[NAME_MAX
];
160 char *last_period
= NULL
, *iter
;
162 if (*filename
== '.')
163 { fprintf (stderr
, HIDDEN_WARNING
);
166 /* Copy the filename and remove its suffix */
167 strncpy(fname
,filename
,NAME_MAX
);
169 for (iter
= fname
; *iter
; iter
++) //find the last '.' char
172 if (last_period
) //if we found one,
173 *last_period
= '\0'; //truncate the string there
174 /* Register the current_filename */
175 current_filename
= filename
;
177 return lexer_lex(fname
);
180 char const* lexer_get_current_filepath
182 { static char current_path
[PATH_MAX
];
183 static char const* last_filename
;
184 if ((!last_filename
|| last_filename
!= current_filename
) &&
185 (realpath(current_filename
, current_path
) != current_path
))
186 { perror("realpath: ");
189 return (const char*)current_path
;