hakyll-4.12.0.1: A static website compiler library

Safe HaskellNone
LanguageHaskell2010

Hakyll.Core.Identifier.Pattern

Contents

Description

As Identifier is used to specify a single item, a Pattern is used to specify a list of items.

In most cases, globs are used for patterns.

A very simple pattern of such a pattern is "foo/bar". This pattern will only match the exact foo/bar identifier.

To match more than one identifier, there are different captures that one can use:

  • "*": matches at most one element of an identifier;
  • "**": matches one or more elements of an identifier.

Some examples:

  • "foo/*" will match "foo/bar" and "foo/foo", but not "foo/bar/qux";
  • "**" will match any identifier;
  • "foo/**" will match "foo/bar" and "foo/bar/qux", but not "bar/foo";
  • "foo/*.html" will match all HTML files in the "foo/" directory.

The capture function allows the user to get access to the elements captured by the capture elements in a glob or regex pattern.

Synopsis

The pattern type

data Pattern Source #

Type that allows matching on identifiers

Creating patterns

fromGlob :: String -> Pattern Source #

Parse a pattern from a string

fromList :: [Identifier] -> Pattern Source #

Create a Pattern from a list of Identifiers it should match.

Warning: use this carefully with hasNoVersion and hasVersion. The Identifiers in the list already have versions assigned, and the pattern will then only match the intersection of both versions.

A more concrete example,

fromList ["foo.markdown"] .&&. hasVersion "pdf"

will not match anything! The "foo.markdown" Identifier has no version assigned, so the LHS of .&&. will only match this Identifier with no version. The RHS only matches Identifiers with version set to "pdf" -- hence, this pattern matches nothing.

The correct way to use this is:

fromList $ map (setVersion $ Just "pdf") ["foo.markdown"]

fromRegex :: String -> Pattern Source #

Create a Pattern from a regex

Example:

regex "^foo/[^x]*$

fromVersion :: Maybe String -> Pattern Source #

Create a pattern which matches all items with the given version.

hasVersion :: String -> Pattern Source #

Specify a version, e.g.

"foo/*.markdown" .&&. hasVersion "pdf"

hasNoVersion :: Pattern Source #

Match only if the identifier has no version set, e.g.

"foo/*.markdown" .&&. hasNoVersion

Composing patterns

(.&&.) :: Pattern -> Pattern -> Pattern infixr 3 Source #

&& for patterns: the given identifier must match both subterms

(.||.) :: Pattern -> Pattern -> Pattern infixr 2 Source #

|| for patterns: the given identifier must match any subterm

complement :: Pattern -> Pattern Source #

Inverts a pattern, e.g.

complement "foo/bar.html"

will match anything except "foo/bar.html"

Applying patterns

matches :: Pattern -> Identifier -> Bool Source #

Check if an identifier matches a pattern

filterMatches :: Pattern -> [Identifier] -> [Identifier] Source #

Given a list of identifiers, retain only those who match the given pattern

Capturing strings

capture :: Pattern -> Identifier -> Maybe [String] Source #

Match a glob or regex pattern against an identifier, generating a list of captures

fromCapture :: Pattern -> String -> Identifier Source #

Create an identifier from a pattern by filling in the captures with a given string

Example:

fromCapture (fromGlob "tags/*") "foo"

Result:

"tags/foo"

fromCaptures :: Pattern -> [String] -> Identifier Source #

Create an identifier from a pattern by filling in the captures with the given list of strings

Orphan instances