c7c459d47b
This reverts commit e4c50b2b09.
Lists are efficient enough and make it easier to customize the trie construction.
Keep the `donotinline` though.
56 lines
1.8 KiB
Text
56 lines
1.8 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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A combinator for building Pratt parsers
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-/
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prelude
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import init.lean.parser.token
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namespace lean.parser
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open monad_parsec combinators
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variables {base_m : Type → Type}
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variables [monad base_m] [monad_basic_read base_m] [monad_state parser_state base_m] [monad_parsec syntax base_m]
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local notation `m` := rec_t nat syntax base_m
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local notation `parser` := m syntax
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def curr_lbp : m nat :=
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do st ← get,
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except.ok tk ← (monad_lift $ observing $ lookahead token) <* put st | pure 0 <* put st,
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match tk with
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| syntax.atom ⟨_, sym⟩ := do
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st ← get,
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some ⟨_, tk_cfg⟩ ← pure (st.tokens.match_prefix sym.mk_iterator) | error "curr_lbp: unreachable",
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pure tk_cfg.lbp
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| syntax.node ⟨base10_lit, _⟩ := pure max_prec
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| syntax.node ⟨id, _⟩ := pure max_prec
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| _ := error "curr_lbp: unknown token kind"
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private def trailing_loop (trailing : reader_t syntax m syntax) (rbp : nat) : nat → syntax → parser
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| 0 _ := error "unreachable"
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| (n+1) left := do
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lbp ← curr_lbp,
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if rbp < lbp then do
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left ← trailing.run left,
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trailing_loop n left
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else
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pure left
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variables [monad_except (parsec.message syntax) base_m] [alternative base_m]
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variables (leading : m syntax) (trailing : reader_t syntax m syntax)
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def pratt_parser (rbp := 0) : base_m syntax :=
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with_recurse rbp $ λ rbp, do
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left ← leading,
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n ← remaining,
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trailing_loop trailing rbp (n+1) left
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instance pratt_parser.tokens [has_tokens leading] [has_tokens trailing] : has_tokens (pratt_parser leading trailing) :=
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⟨has_tokens.tokens leading ++ has_tokens.tokens trailing⟩
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instance pratt_parser.view : has_view (pratt_parser leading trailing) syntax :=
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default _
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end lean.parser
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