125 lines
3.3 KiB
Haskell
125 lines
3.3 KiB
Haskell
{-# LANGUAGE ScopedTypeVariables #-}
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{-|
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Easy regular expression helpers, based on regex-tdfa and regexpr. These should
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- have mnemonic names
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- have simple monomorphic types
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- work with strings
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- support extended regular expressions
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- support replacement
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- support splitting
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- support unicode
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- be cross-platform, not requiring C libraries
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-}
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module Hledger.Utils.Regex (
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Regexp
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,Replacement
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-- ,regexMatch
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-- ,regexMatchCI
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,regexMatches
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,regexMatchesCI
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,containsRegex
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,regexReplace
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,regexReplaceCI
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,regexReplaceBy
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,regexToCaseInsensitive
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,regexSplit
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,toRegex
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)
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where
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import Data.List (foldl')
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import Text.RegexPR (splitRegexPR)
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import Text.Regex.TDFA (
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Regex, CompOption(..), ExecOption(..), defaultCompOpt, defaultExecOpt,
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makeRegexOpts, AllMatches(getAllMatches), match, (=~)
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)
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type Regexp = String
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type Replacement = String
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containsRegex :: Regexp -> String -> Bool
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containsRegex = regexMatchesCI
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regexToCaseInsensitive :: Regexp -> Regexp
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regexToCaseInsensitive r = "(?i)"++ r
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-- regexpr - may be slow
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regexSplit :: Regexp -> String -> [Regexp]
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regexSplit = splitRegexPR
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-- regexMatch :: Regexp -> String -> MatchFun Maybe
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-- regexMatch r s = matchRegexPR r s
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-- regexMatchCI :: Regexp -> String -> MatchFun Maybe
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-- regexMatchCI r s = regexMatch (regexToCaseInsensitive r) s
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-- regexMatches :: Regexp -> String -> Bool
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-- regexMatches r s = isJust $ matchRegexPR r s
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-- regexMatchesCI :: Regexp -> String -> Bool
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-- regexMatchesCI r s = regexMatches (regexToCaseInsensitive r) s
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-- regexReplace :: Regexp -> Replacement -> String -> String
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-- regexReplace r repl s = gsubRegexPR r repl s
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-- regexReplaceCI :: Regexp -> Replacement -> String -> String
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-- regexReplaceCI r s = regexReplace (regexToCaseInsensitive r) s
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-- regexReplaceBy :: Regexp -> (String -> Replacement) -> String -> String
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-- regexReplaceBy r replfn s = gsubRegexPRBy r replfn s
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-- regex-tdfa
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-- | Convert our string-based regexps to real ones. Can fail if the
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-- string regexp is malformed.
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toRegex :: Regexp -> Regex
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toRegex = makeRegexOpts compOpt execOpt
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compOpt :: CompOption
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compOpt = defaultCompOpt
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execOpt :: ExecOption
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execOpt = defaultExecOpt
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-- regexMatch' :: RegexContext Regexp String a => Regexp -> String -> a
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-- regexMatch' r s = s =~ (toRegex r)
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regexMatches :: Regexp -> String -> Bool
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regexMatches = flip (=~)
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regexMatchesCI :: Regexp -> String -> Bool
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regexMatchesCI r = match (makeRegexOpts compOpt{caseSensitive=False} execOpt r)
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regexReplace :: Regexp -> Replacement -> String -> String
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regexReplace r repl = regexReplaceBy r (const repl)
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regexReplaceCI :: Regexp -> Replacement -> String -> String
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regexReplaceCI r s = regexReplace (regexToCaseInsensitive r) s
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regexReplaceBy :: Regexp -> (String -> Replacement) -> String -> String
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regexReplaceBy r = replaceAll (toRegex r)
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-- from http://stackoverflow.com/questions/9071682/replacement-substition-with-haskell-regex-libraries
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replaceAll :: Regex -> (String -> Replacement) -> String -> String
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replaceAll re f s = start end
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where
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(_, end, start) = foldl' go (0, s, id) $ getAllMatches $ match re s
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go (ind,read,write) (off,len) =
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let (skip, start) = splitAt (off - ind) read
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(matched, remaining) = splitAt len start
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in (off + len, remaining, write . (skip++) . (f matched ++))
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