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elinks/src/dom/scanner.h

294 lines
9.3 KiB
C

#ifndef EL_DOM_SCANNER_H
#define EL_DOM_SCANNER_H
#include "dom/string.h"
#include "util/error.h"
/* API Doc :: dom-scanner */
/* Define if you want a talking scanner */
/* #define DEBUG_DOM_SCANNER */
/** DOM scanner token
*
* This struct describes one scanner state. There are two kinds of tokens: char
* and non-char tokens. Char tokens contains only one char and simply have
* their char value as type. They are tokens having special control meaning in
* the code, like ':', ';', '{', '}' and '*'. Non-char tokens have one or more
* chars and contain stuff like number or indentifier strings. */
struct dom_scanner_token {
/** The type the token. */
int type;
/** Some precedence value. */
int precedence;
/** The line number; used for error tokens. */
unsigned int lineno;
/** The start of the token string and the token length. */
struct dom_string string;
};
/** Skip the first charector of a token */
#define skip_dom_scanner_token_char(token) \
do { (token)->string.string++; (token)->string.length--; } while (0)
/** Compare the token string to a "static" string */
#define dom_scanner_token_contains(token, str) \
((token)->string.length == (sizeof(str) - 1) \
&& !strncasecmp((token)->string.string, str, sizeof(str) - 1))
struct dom_scan_table_info {
enum { DOM_SCAN_RANGE, DOM_SCAN_STRING, DOM_SCAN_END } type;
struct dom_string data;
int bits;
};
#define DOM_SCAN_TABLE_SIZE 256
#define DOM_SCAN_TABLE_INFO(type, data1, data2, bits) \
{ (type), INIT_DOM_STRING((data1), (data2)), (bits) }
#define DOM_SCAN_TABLE_RANGE(from, to, bits) \
DOM_SCAN_TABLE_INFO(DOM_SCAN_RANGE, from, to, bits)
#define DOM_SCAN_TABLE_STRING(str, bits) \
DOM_SCAN_TABLE_INFO(DOM_SCAN_STRING, str, sizeof(str) - 1, bits)
#define DOM_SCAN_TABLE_END \
DOM_SCAN_TABLE_INFO(DOM_SCAN_END, NULL, 0, 0)
struct dom_scanner_string_mapping {
struct dom_string name;
int type;
int base_type;
};
#define DOM_STRING_MAP(str, type, family) \
{ STATIC_DOM_STRING(str), (type), (family) }
#define DOM_STRING_MAP_END \
{ INIT_DOM_STRING(NULL, 0), 0, 0 }
struct dom_scanner;
/** DOM scanner info
*
* Backend-specific information used during the actual scanning and
* by the front end to fill the token table on-demand, etc.
*/
struct dom_scanner_info {
/** Table containing how to map strings to token types */
const struct dom_scanner_string_mapping *mappings;
/** Information for how to initialize the scanner table */
const struct dom_scan_table_info *scan_table_info;
/**
* Fills the scanner with tokens. Already scanned tokens which have not
* been requested remain and are moved to the start of the scanners
* token table. Returns the current token or NULL if there are none. */
struct dom_scanner_token *(*scan)(struct dom_scanner *scanner);
/**
* The scanner table. Contains bitmaps for the various characters
* groups. Idea sync'ed from mozilla browser. */
int scan_table[DOM_SCAN_TABLE_SIZE];
/** Has the scanner info been initialized? */
unsigned int initialized:1;
};
/** Initializes a DOM scanner
*
* See struct ref:[dom_scanner] for a description of the `int` flags. */
void init_dom_scanner(struct dom_scanner *scanner, struct dom_scanner_info *scanner_info,
struct dom_string *string, int state, int count_lines, int complete,
int check_complete, int detect_error);
/** The number of tokens in the scanners token table
*
* At best it should be big enough to contain properties with space separated
* values and function calls with up to 3 variables like rgb(). At worst it
* should be no less than 2 in order to be able to peek at the next token in
* the scanner. */
#define DOM_SCANNER_TOKENS 10
/** DOM scanner
*
* Holds the current state of the scanner. */
struct dom_scanner {
/** The start of the scanned string. */
unsigned char *string;
/** The end of the scanned string. */
unsigned char *end;
/**
* The position in the string where to scan next and the end of the
* string. If position is NULL it means that no more tokens can be
* retrieved from the string. */
unsigned char *position;
/**
* The current token. If the number of scanned tokens is less than
* ref:[DOM_SCANNER_TOKENS] it is because there are no more tokens in
* the string. */
struct dom_scanner_token *current;
/** The number of scanned tokens left in the table. */
int tokens;
/** The 'meta' scanner information */
struct dom_scanner_info *info;
#ifdef DEBUG_SCANNER
/* Debug info about the caller. */
unsigned char *file;
int line;
#endif
/* The following two flags are used when parsing is incremental and
* the scanner must ensure that only tokens that are complete are
* generated. */
unsigned int check_complete:1; /*: Only generate complete tokens */
unsigned int incomplete:1; /*: The scanned string is incomplete */
unsigned int detect_errors:1; /*: Check for markup errors */
unsigned int found_error; /*: Did we already report this error? */
unsigned int count_lines:1; /*: Is line counting enbaled? */
unsigned int lineno; /*: Line # of the last scanned token */
/** Some state indicator only meaningful to the scanner internals */
int state;
/**
* The table contain already scanned tokens. It is maintained in
* order to optimize the scanning a bit and make it possible to look
* ahead at the next token. You should always use the accessors
* (defined below) for getting tokens from the scanner. */
struct dom_scanner_token table[DOM_SCANNER_TOKENS];
};
/** Check if there are more tokens */
#define dom_scanner_has_tokens(scanner) \
((scanner)->tokens > 0 && (scanner)->current < (scanner)->table + (scanner)->tokens)
/* This macro checks if the current scanner state is valid. Meaning if the
* scanners table is full the last token skipping or get_next_scanner_token()
* call made it possible to get the type of the next token. */
#define check_dom_scanner(scanner) \
(scanner->tokens < DOM_SCANNER_TOKENS \
|| scanner->current + 1 < scanner->table + scanner->tokens)
/* Scanner table accessors and mutators */
/** Check the type of the next token */
#define check_next_dom_scanner_token(scanner, token_type) \
(scanner_has_tokens(scanner) \
&& ((scanner)->current + 1 < (scanner)->table + (scanner)->tokens) \
&& (scanner)->current[1].type == (token_type))
/** Get the current token */
static inline struct dom_scanner_token *
get_dom_scanner_token(struct dom_scanner *scanner)
{
return dom_scanner_has_tokens(scanner) ? scanner->current : NULL;
}
/** Get the next token
*
* Getting the next token might cause a rescan so any token pointers that has
* been stored in a local variable might not be valid after the call. */
/* Do a scanning if we do not also have access to next token. */
static inline struct dom_scanner_token *
get_next_dom_scanner_token(struct dom_scanner *scanner)
{
return (dom_scanner_has_tokens(scanner)
&& (++scanner->current + 1 >= scanner->table + scanner->tokens)
? scanner->info->scan(scanner) : get_dom_scanner_token(scanner));
}
/** Skip the current token */
#define skip_dom_scanner_token(scanner) get_next_dom_scanner_token(scanner)
/** Conditionally skip tokens
*
* Removes tokens from the scanner until it meets a token of the given type.
* This token will then also be skipped. */
struct dom_scanner_token *
skip_dom_scanner_tokens(struct dom_scanner *scanner, int skipto, int precedence);
/** Map a string to internal ID
*
* Looks up the string from @ident to @end to in the scanners string mapping
* table. */
int
map_dom_scanner_string(struct dom_scanner *scanner,
unsigned char *ident, unsigned char *end, int base_type);
#ifdef DEBUG_DOM_SCANNER
void dump_dom_scanner(struct dom_scanner *scanner);
#endif
/* The begin_token_scanning() and end_token_scanning() functions provide the
* basic setup and teardown for the rescan function made public via the
* scanner_info->scan member. */
/* Returns NULL if it is not necessary to try to scan for more tokens */
static inline struct dom_scanner_token *
begin_dom_token_scanning(struct dom_scanner *scanner)
{
struct dom_scanner_token *table = scanner->table;
struct dom_scanner_token *table_end = table + scanner->tokens;
int move_to_front = int_max(table_end - scanner->current, 0);
struct dom_scanner_token *current = move_to_front ? scanner->current : table;
size_t moved_size = 0;
assert(scanner->current);
/* Move any untouched tokens */
if (move_to_front) {
moved_size = move_to_front * sizeof(*table);
memmove(table, current, moved_size);
current = &table[move_to_front];
}
/* Clear all unused tokens */
memset(current, 0, sizeof(*table) * DOM_SCANNER_TOKENS - moved_size);
if (!scanner->position) {
scanner->tokens = move_to_front ? move_to_front : -1;
scanner->current = table;
assert(check_dom_scanner(scanner));
return NULL;
}
scanner->tokens = move_to_front;
return table;
}
/* Updates the @scanner struct after scanning has been done. The position
* _after_ the last valid token is taken as the @end argument. */
/* It is ok for @end to be < scanner->table since scanner->tokens will become
* <= 0 anyway. */
static inline struct dom_scanner_token *
end_dom_token_scanning(struct dom_scanner *scanner, struct dom_scanner_token *end)
{
assert(end <= scanner->table + DOM_SCANNER_TOKENS);
scanner->tokens = (end - scanner->table);
scanner->current = scanner->table;
if (scanner->position >= scanner->end)
scanner->position = NULL;
assert(check_dom_scanner(scanner));
return get_dom_scanner_token(scanner);
}
#endif