76 lines
2.3 KiB
Text
76 lines
2.3 KiB
Text
/-
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Copyright (c) 2018 Microsoft Corporation. All rights reserved.
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Released under Apache 2.0 license as described in the file LICENSE.
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Author: Sebastian Ullrich
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Level-level parsers
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-/
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prelude
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import init.lean.parser.pratt
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namespace lean
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namespace parser
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open combinators parser.has_view monad_parsec
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@[derive monad alternative monad_reader monad_parsec monad_except monad_rec monad_basic_parser]
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def level_parser_m := rec_t nat syntax basic_parser_m
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abbreviation level_parser := level_parser_m syntax
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/-- A level parser for a suffix or infix notation that accepts a preceding term level. -/
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@[derive monad alternative monad_reader monad_parsec monad_except monad_rec monad_basic_parser]
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def trailing_level_parser_m := reader_t syntax level_parser_m
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abbreviation trailing_level_parser := trailing_level_parser_m syntax
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instance trailing_level_parser_coe : has_coe level_parser trailing_level_parser :=
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⟨λ x _, x⟩
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@[derive parser.has_tokens parser.has_view]
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def level.parser (rbp := 0) : level_parser :=
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recurse rbp <?> "universe level"
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namespace level
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/-- Access leading term -/
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def get_leading : trailing_level_parser := read
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instance : has_tokens get_leading := default _
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instance : has_view syntax get_leading := default _
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@[derive parser.has_tokens parser.has_view]
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def paren.parser : level_parser :=
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node! «paren» ["(":max_prec, inner: level.parser 0, ")"]
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@[derive parser.has_tokens parser.has_view]
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def leading.parser : level_parser :=
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node_choice! leading {
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max: symbol_or_ident "max",
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imax: symbol_or_ident "imax",
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hole: symbol "_" max_prec,
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paren: paren.parser,
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lit: number.parser,
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var: ident.parser
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}
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@[derive parser.has_tokens parser.has_view]
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def app.parser : trailing_level_parser :=
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node! app [fn: get_leading, arg: level.parser max_prec]
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@[derive parser.has_tokens parser.has_view]
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def add_lit.parser : trailing_level_parser :=
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node! add_lit [lhs: get_leading, "+", rhs: number.parser]
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@[derive parser.has_tokens parser.has_view]
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def trailing.parser : trailing_level_parser :=
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node_choice! trailing {
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app: app.parser,
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add_lit: add_lit.parser
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}
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end level
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@[derive parser.has_tokens parser.has_view]
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def level_parser.run (p : level_parser) : basic_parser :=
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pratt_parser level.leading.parser level.trailing.parser p
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instance level_parser_coe : has_coe level_parser basic_parser :=
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⟨level_parser.run⟩
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end parser
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end lean
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