deregexp

package module

v1.1.0 Latest Latest Go to latest Published: Dec 17, 2025 License: BSD-2-Clause Imports: 5 Imported by: 1

Details

Valid go.mod file
Redistributable license
Tagged version
Stable version
Learn more about best practices

Repository

github.com/Jille/deregexp

Links

Open Source Insights

README ¶

Deregexp

Deregexp converts a regexp to an expression with substring matches. This expression does not express exactly the same as the regexp, but a superset. It can be used for a cheap first pass filter, or for index lookups.

Examples

$ go run cmd/test/test.go "Mary.+had.+a.+little.+(lamb|sheep)"
"little" AND "Mary" AND "had" AND ("sheep" OR "lamb")

Note that the "a" has been dropped because it is implied by "Mary" and "had".

$ go run cmd/test/test.go "Mary.+had.+(a|no).+little.+(lamb|sheep)"
"little" AND "Mary" AND "had" AND ("sheep" OR "lamb")

Note that the "(a|no)" has been dropped because the "a" is implied by "Mary" and "had", and (TRUE OR "no") is always true.

Known limitations

Case insensitivity is not supported. You can of course use the resulting expression case insensitively, but controlling case sensitivity with (?i) is not supported. Patches are welcome.

Documentation ¶

Overview ¶

Package deregexp converts a regexp to an expression with substring matches. This expression does not express exactly the same as the regexp, but a superset. It can be used for a cheap first pass filter, or for index lookups.

Index ¶

func Longest(regex string) (string, error)
type AndNode
- func (n AndNode) Expr() string
type Node
- func Deregexp(regex string) (Node, error)
- func Treeify(sequences [][]string) Node
type OrNode
- func (n OrNode) Expr() string

Constants ¶

This section is empty.

Variables ¶

This section is empty.

Functions ¶

func Longest ¶ added in v1.1.0

func Longest(regex string) (string, error)

Longest returns the longest literal string that must be in an input to have a chance of matching the regexp. Can be used for cheap prefiltering. An error will only be returned iff the given regexp is invalid. The returned string might end in truncated UTF-8 characters.

Types ¶

type AndNode ¶

type AndNode struct {
	Words    []string
	Children []OrNode
}

AndNode expresses a set of words and OrNodes that must all match for this node to match.

func (AndNode) Expr ¶

func (n AndNode) Expr() string

Expr converts this node to a string.

type Node ¶

type Node interface {
	Expr() string
}

Node is either an AndNode or OrNode in the tree. The tree describes an expression of ANDs and ORs and words.

func Deregexp ¶

func Deregexp(regex string) (Node, error)

func Treeify ¶

func Treeify(sequences [][]string) Node

Treeify simplifies all possible options passed in into a node tree. Treeify tries to make the tree as simple as possible.

type OrNode ¶

type OrNode struct {
	Words    []string
	Children []AndNode
}

OrNode expresses a set of words and AndNodes of which at least one must match for this node to match.

func (OrNode) Expr ¶

func (n OrNode) Expr() string

Expr converts this node to a string.

Source Files ¶

View all Source files

Directories ¶

Path	Synopsis
cmd
test command Binary test prints the expression tree from the regexp given as argv[1].	Binary test prints the expression tree from the regexp given as argv[1].

?	: This menu
/	: Search site
f or F	: Jump to
y or Y	: Canonical URL