package reparse

Represents a parser which can parse value 'a. Use parse functions to evaluate a parser.

parse ?pos input p parses input using parser p from given pos. It returns a tuple 'a * pos which represents a parsed value 'a and the final parser position pos.

Default value for pos is 0.

return v always parses value v.

Examples

module P = Reparse.String.String;;

let input = new P.string_input "" in
let v1 = P.(parse input (return 5)) in
let v2 = P.(parse input (return "hello")) in
v1 = 5 && v2 = "hello"

unit always parses to ():unit value.

ignore p ignore any result from p upon success and return () instead.

fail err_msg returns a parser that always fails with err_msg.

Examples

module P = Reparse.String;;

let input = new P.string_input "" in
let r =
  try
    let _ = P.(parse input (fail "hello error")) in
    assert false
  with e -> e
in
r
= P.Parser
    {offset= 0; line_number= 0; column_number= 0; msg= "hello error"}

bind f p is prefix version of p >>= f.

both p q is evaluates to (a,b) when a is evaluted from p and b is evaluated from q.

map f p is prefix version of p >>| f.

ppx_let syntax support module.

peek_char t parses the next character from input without consuming it. It fails if EOI is reached.

Examples

module P = Reparse.String;;

let p = P.peek_char in
let v = P.parse_string p "hello" in
v = 'h'

Input is not consumed.

peek_char_opt is the exception safe version of peek_char. It returns an option rather than throwing exn when EOI is reached.

peek_string n parse a string of length n without consuming it.

Examples

module P = Reparse.String
open P;;

let p = P.peek_string 5 in
let v = P.parse_string p "hello" in
v = "hello"

Input is not consumed.

any_char parses the next character from input. Fails if input has reached end of input.

Examples

module P = Reparse.String;;

let v = P.(parse_string any_char "hello") in
v = 'h'

unsafe_any_char is same as any_char except the returned char value is not buffered by the input. Important don't use this parser with backtracking parsers such as <|>, alt, any etc.

Note Ensure you call trim_input_buffer after calling this parser.

char c parses character c exactly.

Examples

module P = Reparse.String;;

let p = P.char 'h' in
let v = P.parse_string p "hello" in
v = 'h'

char_if f parses a character c if f c is true.

Examples

module P = Reparse.String;;

let p = P.char_if (function 'a' -> true | _ -> false) in
let v = P.parse_string p "abc" in
v = 'a'

string_cs s parses a string s exactly. String comparison is case sensitive.

Examples

module P = Reparse.String;;

let p = P.string_cs "hello" in
let v = P.parse p (P.of_string "hello world") in
v = "hello"

string_of_chars l converts char list l to string

Examples

module P = Reparse.String;;

let p = P.(take ~sep_by:space next >>= string_of_chars) in
let v = P.parse_string p "h e l l o" in
v = "hello"

take_string n returns a string of length n exactly from input.

take_cstruct n returns a Cstruct.t of length n exactly from input. This is usually a zero copy if input is an unbuffered input type.

unsafe_take_cstruct n reads n bytes exactly from input without buffering. Since the read n bytes is unbuffered, the parser is unable to backtrack beyond position pos + n where pos is the input position before the parser is called.

Note: Ensure that unsafe_take_cstruct is not being run as part of combinators that require backtracking such as <|>, any. Additionally it is recommended to call trim_input_buffer after calling unsafe_take_cstruct.

unsafe_take_cstruct_ne n is same as unsafe_take_cstruct n except that n represents the maximum number of bytes read.

any l parses the value of the first successful parser in list l. Specified parsers in l are evaluated sequentially from left to right. A failed parser doesn't consume any input, i.e. offset is unaffected. The parser fails if none of the parsers in l are evaluated successfully.

Examples

First successful parser result is returned

module P = Reparse.String;;

let p = P.(any [char 'z'; char 'x'; char 'a']) in
let v = P.parse_string p "zabc" in
v = 'z'
;;

let p = P.(any [char 'z'; char 'x'; char 'a']) in
let v = P.parse_string p "xabc" in
v = 'x'
;;

let p = P.(any [char 'z'; char 'x'; char 'a']) in
let v = P.parse_string p "abc" in
v = 'a'

Parser fails when none of the parsers in l are successful.

let p = P.(any [char 'z'; char 'x'; char 'a']) in
let v =
  try
    let _ = P.parse_string p "yyy" in
    false
  with _ -> true
in
v = true

alt p q is p <|> q. See Reparse.Infix.((<|>))

optional p parses Some a if successful and None otherwise. a is the parsed value of p.

Examples

module P = Reparse.String
open P;;

let p = P.(optional (char 'a')) in
let v = P.parse_string p "ab" in
v = Some 'a'
;;

let p = P.(optional (char 'z')) in
let v = P.parse_string p "ab" in
v = None

not_ p parses value () if and only if p fails to parse, otherwise the parse fails.

Examples

module P = Reparse.String;;

let p = P.(not_ (char 'a')) in
let v = P.parse_string p "bbb" in
v = ()

is p parses true if p is successful, false otherwise. Note evaluation of p doesn't consume any input.

Examples

module P = Reparse.String;;

let p = P.(is (char 'b')) in
let v = P.parse_string p "bcb" in
v = true

is_not p parses value true if p fails to parse and false otherwise. Note evaluating p doesn't consume any input.

Examples

module P = Reparse.String;;

let p = P.(is_not (char 'a')) in
let v = P.parse_string p "bbb" in
v = true

recur f returns a recursive parser. Function value f accepts a parser p as its argument and returns a parser q. Parser q in its definition can refer to p and p can refer to q in its own definition. Such parsers are also known as a fixpoint or y combinator.

all parsers parses all parsers in parsers and returns a list of successful parse result. All of the parsers must succeed for all to succeed.

all_unit parsers parses parsers and discards their results. All of the parsers must succeed for all_unit to succeed.

skip ~at_least ~up_to p repeatedly parses p and discards its value. The lower and upper bound of repetition is specified by arguments at_least and up_to respectively. The default value of at_least is 0. The default value of up_to is unspecified, i.e. there is no upper limit. The repetition ends when one of the following occurs:

• p evaluates to failure
• up_to upper bound value is reached The parser encapsulates the count of times p was evaluated successfully.

Examples

module P = Reparse.String;;

let p = P.(skip space) in
let v = P.parse_string p "     " in
v = 5

take ~at_least ~up_to ~sep_by p repeatedly parses p and returns the parsed values. The lower and upper bound of repetition is specified by arguments at_least and up_to respectively. The default value of at_least is 0. The default value of up_to is unspecified, i.e. there is no upper limit. If sep_by is specified then the evaluation of p must be followed by a successful evaluation of sep_by. The parsed value of sep_by is discarded. The repetition ends when one of the following occurs:

• p evaluates to failure
• sep_by evaluates to failure
• up_to upper boudn value is reached The parser fails if the count of repetition of p does not match the value specified by at_least.

Examples

Default behaviour.

module P = Reparse.String;;

let p = P.(take (char 'a')) in
let v = P.parse_string p "aaaaa" in
v = ['a'; 'a'; 'a'; 'a'; 'a']

Specify ~sep_by.

module P = Reparse.String;;

let p = P.(take ~sep_by:(char ',') (char 'a')) in
let v = P.parse_string p "a,a,a,a,a" in
v = ['a'; 'a'; 'a'; 'a'; 'a']

Specify lower bound argument at_least.

module P = Reparse.String;;

let p = P.(take ~at_least:3 ~sep_by:(char ',') (char 'a')) in
let v = P.parse_string p "a,a,a,a,a" in
v = ['a'; 'a'; 'a'; 'a'; 'a']

Lower bound not met results in error.

module P = Reparse.String;;

let p = P.(take ~at_least:5 ~sep_by:(char ',') (char 'a')) in
let v =
  try
    let _ = P.parse_string p "a,a,a,a" in
    false
  with _ -> true
in
v = true

Specify upper bound up_to.

module P = Reparse.String;;

let p = P.(take ~up_to:3 ~sep_by:(char ',') (char 'a')) in
let v = P.parse_string p "a,a,a,a,a" in
v = ['a'; 'a'; 'a']

take_while_cb ~sep_by ~while_ ~on_take p repeatedly parses p and calls callback on_take_cb with the parsed value. p is evaluated if and only if while_ evaluates to true. If sep_by is specified then the evaluation of p must be followed by a successful evaluation of sep_by. The parsed value of sep_by is discarded. p is evaluated repeatedly. The repetition ends when one of the following occurs: on_take_cb is the callback function that is called every time p is evaluated.

• p evaluates to failure
• while_ returns false
• sep_by evaluates to failure take_while_cb is the general version of Reparse.take_while. It allows to specify how the value a is to be collected. Note while_ does not consume input.

Examples

module P = Reparse.String
open P;;

let buf = Buffer.create 0 in
let on_take_cb a = Buffer.add_char buf a in
let p =
  P.(take_while_cb (char 'a') ~while_:(is_not (char 'b')) ~on_take_cb)
in
let v = P.parse_string p "aaab" in
let s = Buffer.contents buf in
v = 3 && s = "aaa"

take_while ~sep_by p ~while_ p repeatedly parses p and returns its value. p is evaluated if and only if while_ evaluates to true. If sep_by is specified then the evaluation of p must be followed by a successful evaluation of sep_by. The parsed value of sep_by is discarded. The repetition ends when one of the following occurs:

• p evaluates to failure
• while_ returns false
• sep_by evaluates to failure Note while_ does not consume input.

Examples

Default behaviour.

module P = Reparse.String;;

let p = P.(take_while ~while_:(is_not (char 'b')) (char 'a')) in
let v = P.parse_string p "aab" in
v = ['a'; 'a']

Specify sep_by.

module P = Reparse.String;;

let p =
  P.(
    take_while ~sep_by:(char ',') ~while_:(is_not (char 'b')) (char 'a'))
in
let v = P.parse_string p "a,a,ab" in
v = ['a'; 'a'; 'a']

take_between ~sep_by ~start ~end_ p parses start and then repeatedly parses p while the parsed value of p doesn't equal to parsed value of end_. After the repetition end, it parses end_. The parser returns the list of parsed values of p. Both start and end_ parser values are discarded. If sep_by is specified then the evaluation of p must be followed by a successful evaluation of sep_by. The parsed value of sep_by is discarded. The repetition ends when one of the following occurs:

• p evaluates to failure
• end_ parsed value matches p parsed value
• sep_by evaluates to failure

Examples

module P = Reparse.String;;

let p =
  P.(
    take_between ~sep_by:(char ',') ~start:(P.char '(') ~end_:(char ')')
      next)
in
let v = P.parse_string p "(a,a,a)" in
v = ['a'; 'a'; 'a']

alpha parses a character in range A- Z or a-z.

Examples

module P = Reparse
open P;;

let p = P.(take alpha) in
let v = P.parse_string p "abcdABCD" in
v = ['a'; 'b'; 'c'; 'd'; 'A'; 'B'; 'C'; 'D']

alpha_num parses a character in range A-Z or a-z or 0-9.

Examples

module P = Reparse
open P;;

let p = P.(take alpha_num) in
let v = P.parse_string p "ab123ABCD" in
v = ['a'; 'b'; '1'; '2'; '3'; 'A'; 'B'; 'C'; 'D']

lower_alpha parses a character in range a-z.

Examples

module P = Reparse
open P;;

let p = P.(take lower_alpha) in
let v = P.parse_string p "abcd" in
v = ['a'; 'b'; 'c'; 'd']

upper_alpha parses a character in range A-Z.

Examples

module P = Reparse
open P;;

let p = P.(take upper_alpha) in
let v = P.parse_string p "ABCD" in
v = ['A'; 'B'; 'C'; 'D']

bit parses a character which is either '0' or '1'.

Examples

module P = Reparse;;

let p = P.(take bit) in
let v = P.parse_string p "0110 ab" in
v = ['0'; '1'; '1'; '0']

ascii_char parses any US-ASCII character.

Examples

module P = Reparse;;

let p = P.(take ascii_char) in
let v = P.parse_string p "0110 abc '" in
v = ['0'; '1'; '1'; '0'; ' '; 'a'; 'b'; 'c'; ' '; '\'']

cr parses character '\r'.

Examples

module P = Reparse;;

let v = P.(parse_string cr "\rab") in
v = '\r'

crlf parses string "\r\n".

Examples

module P = Reparse;;

let v = P.(parse_string crlf "\r\n abc") in
v = "\r\n"

control parses characters in range 0x00 - 0x1F or character 0x7F.

Examples

module P = Reparse;;

let v = P.(parse_string control "\x00") in
v = '\x00'

digit parses one of the digit characters, 0 .. 9.

Examples

module P = Reparse;;

let p = P.(take digit) in
let v = P.parse_string p "0123456789a" in
v = ['0'; '1'; '2'; '3'; '4'; '5'; '6'; '7'; '8'; '9']

digits parses one or more digit characters, 0 .. 9.

Examples

module P = Reparse;;

let v = P.(parse_string digits "1234 +") in
v = "1234"

dquote parses double quote character '"'.

Examples

module P = Reparse;;

let v = P.(parse_string dquote "\"hello ") in
v = '"'

hex_digit parses any of the hexadecimal digits - 0..9, A, B, C, D, E, F.

Examples

module P = Reparse;;

let p = P.(take hex_digit) in
let v = P.parse_string p "0ABCDEFa" in
v = ['0'; 'A'; 'B'; 'C'; 'D'; 'E'; 'F']

htab parses a horizontal tab character '\t'.

Examples

module P = Reparse;;

let v = P.(parse_string htab "\t") in
v = '\t'

lf parses a linefeed '\n' character.

Examples

module P = Reparse;;

let v = P.(parse_string lf "\n") in
v = '\n'

octect parses any character in the range \x00 - \xFF. Synonym for Reparse.next

Examples

module P = Reparse;;

let p = P.(take octet) in
let v = P.parse_string p "0110 abc '" in
v = ['0'; '1'; '1'; '0'; ' '; 'a'; 'b'; 'c'; ' '; '\'']

space parses a space character.

Examples

module P = Reparse;;

let v = P.(parse_string space " abc '") in
v = ' '

vchar parses any of the visible - printable - characters.

Examples

module P = Reparse;;

let p = P.(take vchar) in
let v = P.parse_string p "0110abc\x00" in
v = ['0'; '1'; '1'; '0'; 'a'; 'b'; 'c']

whitespace parses a space ' ' or horizontal tab '\t' character.

Examples

module P = Reparse;;

let p = P.(take whitespace) in
let v = P.parse_string p "\t \t " in
v = ['\t'; ' '; '\t'; ' ']

advance n advances input by n bytes.

eoi parses end of input. Fails if parser is not at end of input.

Examples

module P = Reparse.String;;

let v = P.(parse_string eoi "") in
v = ()
;;

let v =
  try
    let _ = P.(parse_string eoi "a") in
    false
  with _ -> true
in
v = true

trim_input_buffer () calls INPUT.trim_buffer with the current parser position. Use this function to control the memory consumption of the input buffer.

Note Once trimmed the parser is unable to backtrack beyond the position of last_trimmed_pos. This may affect a correct functioning of <|> parser as it backtracks when trying various alternatives.

pos returns the current parser position.

last_trimmed_pos returns the last trimmed input position marker.

input_buffer_size returns current input buffer size in bytes if input is a buffered input otherwise it returns None for unbuffered input.