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feat: improve leadingIdentAsSymbol trick

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Leonardo de Moura 2020-01-13 16:42:49 -08:00
parent 397addb958
commit 2f5f00ed4f
1 changed files with 6 additions and 5 deletions
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11
src/Init/Lean/Parser/Parser.lean
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@ -1239,11 +1239,10 @@ instance ParsingTables.inhabited : Inhabited ParsingTables := ⟨{}⟩
The field `leadingIdentAsSymbol` specifies how the parsing table lookup function behaves for identifiers.
The function `prattParser` uses two tables `leadingTable` and `trailingTable`. They map tokens to
parsers. If `leadingIdentAsSymbol == false` and the leading token is an identifier, then `prattParser`
just executes the parsers associated with the token "ident".
just executes the parsers associated with the auxiliary token "ident".
If `leadingIdentAsSymbol == true` and the leading token is an identifier `<foo>`, then `prattParser`
first checks whether the `leadingTable` has parsers associated with `<foo>` or not. If there are parsers,
then they are executed. Otherwise, we search for the token "ident".
We use this feature and the `nonReservedSymbol` parser to implement the `tactic` parsers.
combines the parsers associated with the token `<foo>` with the parsers associated with the auxiliary token "ident".
We use this feature and a variant of the `nonReservedSymbol` parser to implement the `tactic` parsers.
We use this approach to avoid creating a reserved symbol for each builtin tactic (e.g., `apply`, `assumption`, etc.).
That is, users may still use these symbols as identifiers (e.g., naming a function).
-/
@ -1280,7 +1279,9 @@ match stx with
| some (Syntax.ident _ _ val _) =>
if leadingIdentAsSymbol then
match map.find val with
| some as => (s, as)
| some as => match map.find `ident with
| some as' => (s, as ++ as')
| _ => (s, as)
| none => find `ident
else
find `ident