ptera-th: A parser generator

[ library, parsing ] [ Propose Tags ]

Ptera is haskell libraries and toolchains for generating parser.


[Skip to Readme]

Flags

Manual Flags

NameDescriptionDefault
develop

Turn on some options for development

Disabled

Use -f <flag> to enable a flag, or -f -<flag> to disable that flag. More info

Downloads

Maintainer's Corner

For package maintainers and hackage trustees

Candidates

Versions [RSS] 0.1.0.0, 0.2.0.0, 0.3.0.0, 0.4.0.0, 0.5.0.0, 0.6.0.0, 0.6.1.0
Change log CHANGELOG.md
Dependencies array (>=0.5.4 && <0.6), base (>=4.14.0 && <5), containers (>=0.6.0 && <0.7), enummapset-th (>=0.6.0 && <0.7), ghc-prim (>=0.6.1 && <0.7), membership (>=0.0.1 && <0.1), ptera (>=0.3.0 && <0.4), ptera-core (>=0.1.0 && <0.2), template-haskell (>=2.16.0 && <2.17), unordered-containers (>=0.2.0 && <0.3) [details]
License (Apache-2.0 OR MPL-2.0)
Copyright (c) 2021 Mizunashi Mana
Author Mizunashi Mana
Maintainer mizunashi-mana@noreply.git
Category Parsing
Home page https://github.com/mizunashi-mana/ptera
Bug tracker https://github.com/mizunashi-mana/ptera/issues
Source repo head: git clone https://github.com/mizunashi-mana/ptera.git
Uploaded by mizunashi_mana at 2022-05-17T14:38:15Z
Distributions NixOS:0.6.1.0
Downloads 118 total (11 in the last 30 days)
Rating (no votes yet) [estimated by Bayesian average]
Your Rating
  • λ
  • λ
  • λ
Status Docs available [build log]
Last success reported on 2022-05-17 [all 1 reports]

Readme for ptera-th-0.6.1.0

[back to package description]

Ptera: A Parser Generator for PEGs

Hackage

Installation

Add dependencies on package.cabal:

build-depends:
    base,
    ptera,          -- main
    ptera-th,       -- for outputing parser with Template Haskell
    template-haskell,

Usage

Write parser rules:

module Parser.Rules where

import Language.Haskell.TH
import Language.Parser.Ptera.TH

data Token
    = TokDigit
    | TokSymPlus
    | TokSymMulti
    | TokEndOfInput
    deriving (Eq, Show, Enum)

data Ast
    = Value
    | Sum Ast Ast
    | Product Ast Ast

$(genGrammarToken (mkName "Tokens") [t|Token|]
    [ ("+", [p|TokSymPlus|])
    , ("*", [p|TokSymMulti|])
    , ("n", [p|TokDigit|])
    , ("^Z", [p|TokEndOfInput{}|])
    ])

$(Ptera.genRules
    do TH.mkName "RuleDefs"
    do GenRulesTypes
        { genRulesCtxTy = [t|()|]
        , genRulesTokensTy = [t|Tokens|]
        , genRulesTokenTy = [t|Token|]
        }
    [ (TH.mkName "ruleExprEos", "expr ^Z", [t|Ast|])
    , (TH.mkName "ruleExpr", "expr", [t|Ast|])
    , (TH.mkName "ruleSum", "sum", [t|Ast|])
    , (TH.mkName "ruleProduct", "product", [t|Ast|])
    , (TH.mkName "ruleValue", "value", [t|Ast|])
    ]
    )

$(Ptera.genParsePoints
    do TH.mkName "ParsePoints"
    do TH.mkName "RuleDefs"
    [ "expr ^Z"
    ]
    )

grammar :: Grammar RuleDefs Tokens Token ParsePoints
grammar = fixGrammar $ RuleDefs
    { ruleExprEos = rExprEos
    , ruleExpr = rExpr
    , ruleSum = rSum
    , ruleProduct = rProduct
    , ruleValue = rValue
    }

type Rule = RuleExpr RuleDefs Tokens Token


rExprEos :: Rule Ast
rExprEos = ruleExpr
    [ varA @"expr" <^> tokA @"^Z"
        <:> \(e :* _ :* HNil) -> e
    ]

rExpr :: Rule Ast
rExpr = ruleExpr
    [ varA @"sum"
        <:> \(e :* HNil) -> e
    ]

rSum :: Rule Ast
rSum = ruleExpr
    [ varA @"product" <^> tokA @"+" <^> varA @"sum"
        <:> \(e1 :* _ :* e2 :* HNil) -> [|| Sum $$(e1) $$(e2) ||]
    , varA @"product"
        <:> \(e :* HNil) -> e
    ]

rProduct :: Rule Ast
rProduct = ruleExpr
    [ varA @"value" <^> tokA @"*" <^> varA @"product"
        <:> \(e1 :* _ :* e2 :* HNil) -> [|| Product $$(e1) $$(e2) ||]
    , varA @"value"
        <:> \(e :* HNil) -> e
    ]

rValue :: Rule Ast
rValue = ruleExpr
    [ tokA @"n" <:> \(n :* HNil) ->
        [|| case $$(n) of
            TokDigit -> Value
            _        -> error "unreachable: expected digit token"
        ||]
    ]

And, generate parser:

module Parser where

import Parser.Rules
import Language.Parser.Ptera.TH
import Data.Proxy

$(genRunner
    (GenParam
        { startsTy = [t|ParsePoints|]
        , rulesTy  = [t|RuleDefs|]
        , tokensTy = [t|Tokens|]
        , tokenTy  = [t|Token|]
        , customCtxTy = defaultCustomCtxTy
        })
    grammar
    )

exprParser :: Scanner posMark Token m => m (Result posMark Ast)
exprParser = runParser (Proxy :: Proxy "expr EOS") pteraTHRunner

Examples