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
,** lexer_direntpb
;
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
61 lexer as a stack, and is popped as a FIFO stack.
63 #define DE_STACK (lexer_direntpa)
64 #define DE_STACKP (lexer_direntpp)
65 #define DE_STACKB (lexer_direntpb)
66 #define DE_LEN() (DE_STACKP - DE_STACKB)
67 #define DE_INIT() (DE_STACKP = DE_STACKB = DE_STACK)
68 #define DE_POP() (*DE_STACKB++)
71 This is a FIFO stack whose pointers are a union of either a pointer to an
72 integer, or a pointer to two integers (a struct tok). This way, integers may
73 be added or removed from the stack either singularly (IPUSH/IPOP), or as a
74 full token of two integers (PUSH/POP).
75 An alignment error will occur if IPOP or IPUSH are used a non-even number of
78 #define TK_STACK (token_stack)
79 #define TK_STACKP (tsp)
80 #define TK_STACKX (tsx)
81 #define TK_LEN() (TK_STACKX - TK_STACKP)
82 #define TK_INIT() (TK_STACKP = TK_STACKX = TK_STACK)
83 #define TK_POP() (*TK_STACKP++)
84 #define TK_PUSH(T,L) (*TK_STACKX++ = (struct tok){L,T})
87 The initializer returns boolean true if an error occurs, which may be handled
94 current_filename
= NULL
;
95 return scanner_init();
99 If the token buffer is empty, 'lexer' will initialize the token buffer and
100 call 'lexer_scandir'. If SCAN_ERROR is returned, an error is printed
101 before sending a null return to bison. If 0 tokens are generated, the error
102 printing is skipped. In all other cases, 'yylval' is set, and the token's
103 integer representation is returned.
107 #define SCAN_ERROR -1
108 #define TK_EMPTY (TK_STACKP == TK_STACKX)
111 fprintf(stderr,__VA_ARGS__); \
117 while (DE_LEN() > 0) //lex any directory entries in our stack
118 if (lexer_lexfile(DE_POP()->d_name
) == 0)
119 FAIL("Lexer failed to tokenize [%s]\n",(*DE_STACKB
)->d_name
);
120 if (TK_EMPTY
) //if there are no tokens,
121 { TK_INIT(); //initialize the token stack back to 0
123 { case SCAN_ERROR
: //if an error occurred,
124 FAIL("Scanner error\n");
125 case 0: //if the the scanner finds no dirents,
126 goto done
; //then we are done
127 default: //if we found some elements to scan,
128 goto start
; //start over and lex them
141 This receiver takes a struct tok and pushes it to the FIFO stack.
144 #define $($)#$ //stringifier
145 #define ERR_TK "Fatal: Generated over " $(TK_STACKSIZE) " tokens in one pass."
146 ( int tok
, YYSTYPE lval
)
147 { if (TK_LEN() >= TK_STACKSIZE
)
148 { fprintf(stderr
, ERR_TK
);
154 /* Lexical analysis of a file
155 Strips a filename to its base name, then sends it to lexer_lex
158 #define HIDDEN_WARNING "%s is hidden and will not be parsed!\n", filename
159 ( const char *filename
161 { static char fname
[NAME_MAX
];
162 char *last_period
= NULL
, *iter
;
164 if (*filename
== '.')
165 { fprintf (stderr
, HIDDEN_WARNING
);
168 /* Copy the filename and remove its suffix */
169 strncpy(fname
,filename
,NAME_MAX
);
171 for (iter
= fname
; *iter
; iter
++) //find the last '.' char
174 if (last_period
) //if we found one,
175 *last_period
= '\0'; //truncate the string there
176 /* Register the current_filename */
177 current_filename
= filename
;
179 return lexer_lex(fname
);
182 char const* lexer_get_current_filepath
184 { static char current_path
[PATH_MAX
];
185 static char const* last_filename
;
186 if ((!last_filename
|| last_filename
!= current_filename
) &&
187 (realpath(current_filename
, current_path
) != current_path
))
188 { perror("realpath: ");
191 return (const char*)current_path
;