Module Str

module Str: sig .. end
Regular expressions and high-level string processing


Regular expressions and high-level string processing

Regular expressions

type regexp 
The type of compiled regular expressions.
val regexp : string -> regexp
Compile a regular expression. The following constructs are recognized:
val regexp_case_fold : string -> regexp
Same as regexp, but the compiled expression will match text in a case-insensitive way: uppercase and lowercase letters will be considered equivalent.
val quote : string -> string
Str.quote s returns a regexp string that matches exactly s and nothing else.
val regexp_string : string -> regexp
Str.regexp_string s returns a regular expression that matches exactly s and nothing else.
val regexp_string_case_fold : string -> regexp
Str.regexp_string_case_fold is similar to Str.regexp_string, but the regexp matches in a case-insensitive way.

String matching and searching

val string_match : regexp -> string -> int -> bool
string_match r s start tests whether a substring of s that starts at position start matches the regular expression r. The first character of a string has position 0, as usual.
val search_forward : regexp -> string -> int -> int
search_forward r s start searches the string s for a substring matching the regular expression r. The search starts at position start and proceeds towards the end of the string. Return the position of the first character of the matched substring, or raise Not_found if no substring matches.
val search_backward : regexp -> string -> int -> int
search_backward r s last searches the string s for a substring matching the regular expression r. The search first considers substrings that start at position last and proceeds towards the beginning of string. Return the position of the first character of the matched substring; raise Not_found if no substring matches.
val string_partial_match : regexp -> string -> int -> bool
Similar to Str.string_match, but also returns true if the argument string is a prefix of a string that matches. This includes the case of a true complete match.
val matched_string : string -> string
matched_string s returns the substring of s that was matched by the latest Str.string_match, Str.search_forward or Str.search_backward. The user must make sure that the parameter s is the same string that was passed to the matching or searching function.
val match_beginning : unit -> int
match_beginning() returns the position of the first character of the substring that was matched by Str.string_match, Str.search_forward or Str.search_backward.
val match_end : unit -> int
match_end() returns the position of the character following the last character of the substring that was matched by string_match, search_forward or search_backward.
val matched_group : int -> string -> string
matched_group n s returns the substring of s that was matched by the nth group \(...\) of the regular expression during the latest Str.string_match, Str.search_forward or Str.search_backward. The user must make sure that the parameter s is the same string that was passed to the matching or searching function. matched_group n s raises Not_found if the nth group of the regular expression was not matched. This can happen with groups inside alternatives \|, options ? or repetitions *. For instance, the empty string will match \(a\)*, but matched_group 1 "" will raise Not_found because the first group itself was not matched.
val group_beginning : int -> int
group_beginning n returns the position of the first character of the substring that was matched by the nth group of the regular expression.
Raises
val group_end : int -> int
group_end n returns the position of the character following the last character of substring that was matched by the nth group of the regular expression.
Raises

Replacement

val global_replace : regexp -> string -> string -> string
global_replace regexp templ s returns a string identical to s, except that all substrings of s that match regexp have been replaced by templ. The replacement template templ can contain \1, \2, etc; these sequences will be replaced by the text matched by the corresponding group in the regular expression. \0 stands for the text matched by the whole regular expression.
val replace_first : regexp -> string -> string -> string
Same as Str.global_replace, except that only the first substring matching the regular expression is replaced.
val global_substitute : regexp -> (string -> string) -> string -> string
global_substitute regexp subst s returns a string identical to s, except that all substrings of s that match regexp have been replaced by the result of function subst. The function subst is called once for each matching substring, and receives s (the whole text) as argument.
val substitute_first : regexp -> (string -> string) -> string -> string
Same as Str.global_substitute, except that only the first substring matching the regular expression is replaced.
val replace_matched : string -> string -> string
replace_matched repl s returns the replacement text repl in which \1, \2, etc. have been replaced by the text matched by the corresponding groups in the most recent matching operation. s must be the same string that was matched during this matching operation.

Splitting

val split : regexp -> string -> string list
split r s splits s into substrings, taking as delimiters the substrings that match r, and returns the list of substrings. For instance, split (regexp "[ \t]+") s splits s into blank-separated words. An occurrence of the delimiter at the beginning and at the end of the string is ignored.
val bounded_split : regexp -> string -> int -> string list
Same as Str.split, but splits into at most n substrings, where n is the extra integer parameter.
val split_delim : regexp -> string -> string list
Same as Str.split but occurrences of the delimiter at the beginning and at the end of the string are recognized and returned as empty strings in the result. For instance, split_delim (regexp " ") " abc " returns [""; "abc"; ""], while split with the same arguments returns ["abc"].
val bounded_split_delim : regexp -> string -> int -> string list
Same as Str.bounded_split, but occurrences of the delimiter at the beginning and at the end of the string are recognized and returned as empty strings in the result.
type split_result = 
| Text of string
| Delim of string
val full_split : regexp -> string -> split_result list
Same as Str.split_delim, but returns the delimiters as well as the substrings contained between delimiters. The former are tagged Delim in the result list; the latter are tagged Text. For instance, full_split (regexp "[{}]") "{ab}" returns [Delim "{"; Text "ab"; Delim "}"].
val bounded_full_split : regexp -> string -> int -> split_result list
Same as Str.bounded_split_delim, but returns the delimiters as well as the substrings contained between delimiters. The former are tagged Delim in the result list; the latter are tagged Text.

Extracting substrings

val string_before : string -> int -> string
string_before s n returns the substring of all characters of s that precede position n (excluding the character at position n).
val string_after : string -> int -> string
string_after s n returns the substring of all characters of s that follow position n (including the character at position n).
val first_chars : string -> int -> string
first_chars s n returns the first n characters of s. This is the same function as Str.string_before.
val last_chars : string -> int -> string
last_chars s n returns the last n characters of s.