Module Netstring_str

module Netstring_str: sig .. end

Wrapper for regexps with Str syntax

This module was written at a time when we had only the Str module for regular expressions. However, Str has an interface that does not work for multi-threaded programs, because the state of the module is visible to the outside. The module Netstring_str is similar to Str, but has a thread-compatible interface.

Now we have the much better PCRE library for regular expressions. This implementation of Netstring_str bases on the PCRE engine but retains the old interface as much as possible. This includes that the regexp function parses old-style regular expressions and internally translates them to PCRE-style expressions.

See also Netstring_pcre. The difference is that Netstring_pcre expects already PCRE-style regular expressions and does not translate them.

Supported regexp syntax

 .             matches every character but newline
 e*            matches e several times
 e+            matches e several times but at least once
 e?            matches e optionally
 e{m,n}        matches e at least m times and at most n times
 e1\|e2        matches e1 or e2
 [set]         matches the characters from set
 [^set]        matches the characters except from set
 \(...\)       group paranthesis
 \n            back reference
 \w            matches word (= alphanumeric characters (and underscore))
 \W            matches characters except \w
 \b            matches at word boundary
 \B            matches everywhere but not at word boundary
 \<            matches at beginning of word
 \>            matches at end of word
 ^             matches at beginning of line
 $             matches at end of line
 \`            matches at beginning of buffer
 \'            matches at end of buffer

This is exactly what Str supports with one exception. Character classes are not implemented.

type regexp = Pcre.regexp

The type of regular expressions; now based on Pcre

type split_result = Str.split_result =

`\|`	`Text of string`
`\|`	`Delim of string`	`(*`	Here we keep compatibility with `Str`	`*)`

type result

The type of matching results

val regexp : string -> regexp

Parses a regexp

val regexp_case_fold : string -> regexp

Parses a case-insensitive regexp

val quote : string -> string

Quotes a string such that it can be included in a regexp

val regexp_string : string -> regexp

Returns a regexp that matches exactly the string

val regexp_string_case_fold : string -> regexp

Returns a case-insensitive regexp that matches exactly the string

Note: the groups argument is ignored in the following functions. Once upon a time this argument determined how many groups were copied to the result value. Now all groups are accessible in the result value, no matter what groups says.

val string_match : ?groups:int ->
       regexp -> string -> int -> result option

Matches the string at the position with the regexp. Returns None if no match is found. Returns Some r on success, and r describes the match.

val search_forward : ?groups:int ->
       regexp -> string -> int -> int * result

Searches a match of the string with the regexp, starting at the position and in forward direction. Raises Not_found if no match could be found. Returns (p,r) when a match at position p is found, described by r.

val search_backward : ?groups:int ->
       regexp -> string -> int -> int * result

Searches a match of the string with the regexp, starting at the position and in backward direction. Raises Not_found if no match could be found. Returns (p,r) when a match at position p is found, described by r.

val matched_string : result -> string -> string

Extracts the matched part from the string. The string argument must be the same string passed to string_match or the search functions, and the result argument must be the corresponding result.

val match_beginning : result -> int

Returns the position where the matched part begins

val match_end : result -> int

Returns the position where the matched part ends

val matched_group : result -> int -> string -> string

Extracts the substring the nth group matches from the whole string. The string argument must be the same string passed to string_match or the search functions, and the result argument must be the corresponding result.

val group_beginning : result -> int -> int

Returns the position where the substring matching the nth group begins

val group_end : result -> int -> int

Returns the position where the substring matching the nth group ends

val global_replace : regexp -> string -> string -> string

global_replace re templ s: Replaces all matchings of re in s by templ.

In templ one can refer to matched groups by the backslash notation: \1 refers to the first group, \2 to the second etc. \0 is the whole match. \\ is the backslash character.

val replace_first : regexp -> string -> string -> string

replace_first re templ s: Replaces the first match of re in s by templ.

In templ one can refer to matched groups by the backslash notation: \1 refers to the first group, \2 to the second etc. \0 is the whole match. \\ is the backslash character.

val global_substitute : ?groups:int ->
       regexp ->
       (result -> string -> string) -> string -> string

global_substitute re subst s: Applies the substitution function subst to all matchings of re in s, and returns the transformed string. subst is called with the current result of the match and the whole string s.

val substitute_first : ?groups:int ->
       regexp ->
       (result -> string -> string) -> string -> string

substitute_first re subst s: Applies the substitution function subst to the first matching of re in s, and returns the transformed string. subst is called with the current result of the match and the whole string s.

val split : regexp -> string -> string list

Splits the string according to the regexp in substrings. Occurrences of the delimiter at the beginning and the end are ignored.

val bounded_split : regexp -> string -> int -> string list

Splits into at most n substrings, based on split

val split_delim : regexp -> string -> string list

Same as split, but occurrences of the delimiter at the beginning and the end are returned as empty strings

val bounded_split_delim : regexp -> string -> int -> string list

Splits into at most n substrings, based on split_delim

val full_split : regexp -> string -> split_result list

Like split_delim, but returns the delimiters in the result

val bounded_full_split : regexp -> string -> int -> split_result list

Splits into at most n substrings, based on full_split

val string_before : string -> int -> string

The first n characters of a string

val string_after : string -> int -> string

The last n characters of a string

val first_chars : string -> int -> string

Same as string_before

val last_chars : string -> int -> string

Same as string_after

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