liblex/include/pattern.h

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#ifndef LIBLEX_PATTERN_H
#define LIBLEX_PATTERN_H
#include "liblex.h"
/**
* Enum that represents the type
* of a NFA node / state.
*/
enum pattern_node_type_e {
/**
* Represents a clear, un-configured node.
*/
PNODE_CLEAR,
/**
* Represents a single value to be matched.
*/
PNODE_VALUE,
/**
* Represents a range of values, inclusive.
*/
PNODE_RANGE,
/**
* Represents any character other than the NULL terminator.
*/
PNODE_ANY,
/**
* Represents a "connection" between nodes, does not
* match any value.
* */
PNODE_CONNECT,
/**
* Represents a fork / divide in possible "next" states.
*/
PNODE_FORK,
/**
* Represents a succesfully matched pattern.
*/
PNODE_END
};
/**
* Struct representing a single NFA node / state.
*/
struct pattern_node_s {
/**
* The type of this node.
*/
enum pattern_node_type_e type;
/**
* The id of this node.
* The id is unique within the pattern.
*/
int id;
/**
* The id of the pattern that this node belongs to.
*/
int pattern_id;
/**
* The node's data that varies based on type.
*/
union {
/**
* Data for a "value" node.
*/
struct {
/**
* The value this node matches.
*/
char value;
/**
* The next state in the pattern.
*/
struct pattern_node_s* next;
} value_s;
/**
* Data for a "range" node.
*/
struct {
/**
* The beginning of the range, inclusive, of matched values.
*/
char from;
/**
* The end of the range, inclusive, of matched values.
*/
char to;
/**
* The next state in the pattern.
*/
struct pattern_node_s* next;
} range_s;
/**
* Data for an "any" node.
*/
struct {
/**
* The next state in the pattern.
*/
struct pattern_node_s* next;
} any_s;
/**
* Data for a "connect" node.
*/
struct {
/**
* The next node in the pattern.
*/
struct pattern_node_s* next;
} connect_s;
/**
* Data for a "fork" node.
*/
struct {
/**
* The left node in the fork.
*/
struct pattern_node_s* left;
/**
* The right node in the fork.
*/
struct pattern_node_s* right;
} fork_s;
} data_u;
};
/**
* A chain of pattern nodes.
*/
struct pattern_chain_s {
/**
* The beginning of the chain, its first state.
*/
struct pattern_node_s* head;
/**
* The end of the chain, its last state.
*/
struct pattern_node_s* tail;
};
/**
* Represents a single compiled pattern.
*/
struct pattern_s {
/**
* The first NFA state of the pattern.
*/
struct pattern_node_s* head;
/**
* The number of NFA nodes in this pattern.
*/
int size;
};
typedef enum pattern_node_type_e pattern_node_type;
typedef struct pattern_node_s pattern_node;
typedef struct pattern_chain_s pattern_chain;
typedef struct pattern_s pattern;
/**
* Compiles a string representation of a pattern into a pattern NFA,
* and stores the first node of the new NFA in root.
* @param root the node to store the resulting pattern into.
* @param expression the pattern represented as a string.
* @param id the id of the pattern.
* @return LIBLEX_SUCCESS if all goes well, otherwise some other liblex_result.
*/
liblex_result pattern_compile(pattern* ptrn, char* expression, int id);
/**
* Frees a pattern NFA allocated by pattern_compile.
* @param root the root node to start freeing from.
* @return LIBLEX_SUCCESS if all goes well, otherwise some other liblex_result.
*/
liblex_result pattern_free(pattern* ptrn);
#endif