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+/* vi:set ts=8 sts=4 sw=4 noet:
+ *
+ * NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE
+ *
+ * This is NOT the original regular expression code as written by Henry
+ * Spencer. This code has been modified specifically for use with Vim, and
+ * should not be used apart from compiling Vim. If you want a good regular
+ * expression library, get the original code.
+ *
+ * NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE
+ */
+
+#ifndef _REGEXP_H
+#define _REGEXP_H
+
+/*
+ * The number of sub-matches is limited to 10.
+ * The first one (index 0) is the whole match, referenced with "\0".
+ * The second one (index 1) is the first sub-match, referenced with "\1".
+ * This goes up to the tenth (index 9), referenced with "\9".
+ */
+#define NSUBEXP 10
+
+/*
+ * In the NFA engine: how many braces are allowed.
+ * TODO(RE): Use dynamic memory allocation instead of static, like here
+ */
+#define NFA_MAX_BRACES 20
+
+/*
+ * In the NFA engine: how many states are allowed
+ */
+#define NFA_MAX_STATES 100000
+#define NFA_TOO_EXPENSIVE (-1)
+
+// Which regexp engine to use? Needed for vim_regcomp().
+// Must match with 'regexpengine'.
+#define AUTOMATIC_ENGINE 0
+#define BACKTRACKING_ENGINE 1
+#define NFA_ENGINE 2
+
+typedef struct regengine regengine_T;
+
+/*
+ * Structure returned by vim_regcomp() to pass on to vim_regexec().
+ * This is the general structure. For the actual matcher, two specific
+ * structures are used. See code below.
+ */
+typedef struct regprog
+{
+ regengine_T *engine;
+ unsigned regflags;
+ unsigned re_engine; // automatic, backtracking or nfa engine
+ unsigned re_flags; // second argument for vim_regcomp()
+ int re_in_use; // prog is being executed
+} regprog_T;
+
+/*
+ * Structure used by the back track matcher.
+ * These fields are only to be used in regexp.c!
+ * See regexp.c for an explanation.
+ */
+typedef struct
+{
+ // These four members implement regprog_T
+ regengine_T *engine;
+ unsigned regflags;
+ unsigned re_engine;
+ unsigned re_flags;
+ int re_in_use;
+
+ int regstart;
+ char_u reganch;
+ char_u *regmust;
+ int regmlen;
+#ifdef FEAT_SYN_HL
+ char_u reghasz;
+#endif
+ char_u program[1]; // actually longer..
+} bt_regprog_T;
+
+/*
+ * Structure representing a NFA state.
+ * An NFA state may have no outgoing edge, when it is a NFA_MATCH state.
+ */
+typedef struct nfa_state nfa_state_T;
+struct nfa_state
+{
+ int c;
+ nfa_state_T *out;
+ nfa_state_T *out1;
+ int id;
+ int lastlist[2]; // 0: normal, 1: recursive
+ int val;
+};
+
+/*
+ * Structure used by the NFA matcher.
+ */
+typedef struct
+{
+ // These three members implement regprog_T
+ regengine_T *engine;
+ unsigned regflags;
+ unsigned re_engine;
+ unsigned re_flags;
+ int re_in_use;
+
+ nfa_state_T *start; // points into state[]
+
+ int reganch; // pattern starts with ^
+ int regstart; // char at start of pattern
+ char_u *match_text; // plain text to match with
+
+ int has_zend; // pattern contains \ze
+ int has_backref; // pattern contains \1 .. \9
+#ifdef FEAT_SYN_HL
+ int reghasz;
+#endif
+ char_u *pattern;
+ int nsubexp; // number of ()
+ int nstate;
+ nfa_state_T state[1]; // actually longer..
+} nfa_regprog_T;
+
+/*
+ * Structure to be used for single-line matching.
+ * Sub-match "no" starts at "startp[no]" and ends just before "endp[no]".
+ * When there is no match, the pointer is NULL.
+ */
+typedef struct
+{
+ regprog_T *regprog;
+ char_u *startp[NSUBEXP];
+ char_u *endp[NSUBEXP];
+
+ colnr_T rm_matchcol; // match start without "\zs"
+ int rm_ic;
+} regmatch_T;
+
+/*
+ * Structure to be used for multi-line matching.
+ * Sub-match "no" starts in line "startpos[no].lnum" column "startpos[no].col"
+ * and ends in line "endpos[no].lnum" just before column "endpos[no].col".
+ * The line numbers are relative to the first line, thus startpos[0].lnum is
+ * always 0.
+ * When there is no match, the line number is -1.
+ */
+typedef struct
+{
+ regprog_T *regprog;
+ lpos_T startpos[NSUBEXP];
+ lpos_T endpos[NSUBEXP];
+
+ colnr_T rmm_matchcol; // match start without "\zs"
+ int rmm_ic;
+ colnr_T rmm_maxcol; // when not zero: maximum column
+} regmmatch_T;
+
+/*
+ * Structure used to store external references: "\z\(\)" to "\z\1".
+ * Use a reference count to avoid the need to copy this around. When it goes
+ * from 1 to zero the matches need to be freed.
+ */
+typedef struct
+{
+ short refcnt;
+ char_u *matches[NSUBEXP];
+} reg_extmatch_T;
+
+struct regengine
+{
+ // bt_regcomp or nfa_regcomp
+ regprog_T *(*regcomp)(char_u*, int);
+ // bt_regfree or nfa_regfree
+ void (*regfree)(regprog_T *);
+ // bt_regexec_nl or nfa_regexec_nl
+ int (*regexec_nl)(regmatch_T *, char_u *, colnr_T, int);
+ // bt_regexec_mult or nfa_regexec_mult
+ long (*regexec_multi)(regmmatch_T *, win_T *, buf_T *, linenr_T, colnr_T, int *);
+ //char_u *expr;
+};
+
+// Flags used by vim_regsub() and vim_regsub_both()
+#define REGSUB_COPY 1
+#define REGSUB_MAGIC 2
+#define REGSUB_BACKSLASH 4
+
+#endif // _REGEXP_H