trw

README

trw: Text Re-Writer.

Package trw wraps around various text processing functions from the standard Go library to allow for functional composition of operations, also minimising memory consumption. Here is an example of usage.

About the package

The package is most useful in situations where a number of text rewriting operations is to be applied sequentially to a large input byte slice. For this scenario the package provides:

• Functional composition of the existing or user-defined operations that can later be applied all at once;
• Memory optimisation using various techniques to minimise (re)allocations.

Documentation

Overview

Package trw wraps around various text processing functions from the standard Go library to allow for functional composition of operations, also minimising memory allocations.

Example

package main

import "fmt"

func main() {
	src := []byte("*SomeSome*  example    _text_")
	res := rewriter.Do(src)

	fmt.Println(string(res))
}

var rewriter = Seq(
	Delete(LitN("Some", 1)),
	Replace(Patt(`[[:space:]]+`), " "),
	Expand(`_([^_]+)_`, `<i>${1}</i>`),
	Expand(`\*([^\*]+)\*`, `<b>${1}</b>`),
)

Output:

<b>Some</b> example <i>text</i>

Index

• type Matcher
  • func Lit(patt string) Matcher
  • func LitN(patt string, n int) Matcher
  • func Patt(patt string) Matcher
  • func PattN(patt string, n int) Matcher
  • func Re(re *regexp.Regexp) Matcher
  • func ReN(re *regexp.Regexp, n int) Matcher
• type Rewriter
  • func Delete(match Matcher) Rewriter
  • func Expand(patt, subst string) Rewriter
  • func ExpandN(patt, subst string, n int) Rewriter
  • func ExpandRe(re *regexp.Regexp, subst string) Rewriter
  • func ExpandReN(re *regexp.Regexp, subst string, n int) Rewriter
  • func Replace(match Matcher, subst string) Rewriter
  • func Seq(rewriters ...Rewriter) Rewriter
  • func (rw Rewriter) Do(src []byte) (result []byte)

Examples

• Package

Types

type Matcher

type Matcher = func([]byte) [][]int

Matcher is a type of a function that, given a byte slice, returns a slice holding the index pairs identifying all successive matches, or nil if there is no match.

func Lit

func Lit(patt string) Matcher

Lit creates a Matcher for the given string literal.

func LitN

func LitN(patt string, n int) Matcher

LitN creates a Matcher for the given string literal that matches up to n times.

func Patt

func Patt(patt string) Matcher

Patt creates a Matcher for the given regular expression pattern.

func PattN

func PattN(patt string, n int) Matcher

PattN creates a Matcher for the given regular expression pattern, matching up to n times.

func Re

func Re(re *regexp.Regexp) Matcher

Re creates a matcher for the given regular expression object.

func ReN

func ReN(re *regexp.Regexp, n int) Matcher

ReN creates a matcher for the given regular expression object, matching up to n times.

type Rewriter

type Rewriter func([]byte, []byte) ([]byte, []byte)

Rewriter is an opaque type representing a text rewriting operation.

func Delete

func Delete(match Matcher) Rewriter

Delete creates a Rewriter that removes all the matches produced by the given Matcher.

func Expand

func Expand(patt, subst string) Rewriter

Expand creates a Rewriter that applies Regexp.Expand() operation to every match of the given regular expression pattern.

func ExpandN

func ExpandN(patt, subst string, n int) Rewriter

ExpandN creates a Rewriter that applies Regexp.Expand() operation to the first n matches of the given regular expression pattern.

func ExpandRe

func ExpandRe(re *regexp.Regexp, subst string) Rewriter

ExpandRe creates a Rewriter that applies Regexp.Expand() operation to all matches of the given regular expression object.

func ExpandReN

func ExpandReN(re *regexp.Regexp, subst string, n int) Rewriter

ExpandReN creates a Rewriter that applies Regexp.Expand() operation to the first n matches of the given regular expression object.

func Replace

func Replace(match Matcher, subst string) Rewriter

Replace creates a rewriter that substitutes all the matches produced by the given Matcher with the specified string.

func Seq

func Seq(rewriters ...Rewriter) Rewriter

Seq is a sequential composition of Rewriters.

func (Rewriter) Do

func (rw Rewriter) Do(src []byte) (result []byte)

Do applies the Rewriter to the specified byte slice. The returned result may be either the source slice modified in-place, or a new slice.