Since fileset and revset languages are syntactically close, we can reparse
revset expression as a fileset. This might sound a bit scary, but helps
eliminate nested quoting like file("~glob:'*.rs'"). One oddity exists in alias
substitution, though. Another possible problem is that we'll need to add fake
operator parsing rules if we introduce incompatibility in fileset, or want to
embed revset expressions in a fileset.
Since "file(x, y)" is equivalent to "file(x|y)", the former will be deprecated.
I'll probably add a mechanism to collect warnings during parsing.
The return type T doesn't have to be a literal, and I'm going to use this
function to reparse fileset expression. We might also want to add another
expect_literal_with() helper that parses enum-like string value.
Maybe it'll also be good to keep RevsetExpression::Union(_) flattened, but
that's not needed to get around stack overflow. The constructed expression
tree is balanced.
test_expand_symbol_alias() is slightly adjusted since there are more than
one representation for "a|b|c" now.
Fixes#4031
Still alias function shadows builtin function (of any arity) by name. This
allows to detect argument error as such, but might be a bit inconvenient if
user wants to overload heads() for example. If needed, maybe we can add some
config/revset syntax to import builtin function to alias namespace.
The functions table is keyed by name, not by (name, arity) pair. That's mainly
because std collections require keys to be Borrow, and a pair of borrowed
values is incompatible with owned pair. Another reason is it makes easy to look
up overloads by name.
Alias overloading could also be achieved by adding default parameters, but that
will complicate the implementation a bit more, and can't prevent shadowing of
0-ary immutable_heads().
Closes#2966
I'm going to add arity-based alias overloading, and we'll need function
(name, arity) pair to identify it in alias expansion stack. The exact parameter
names aren't necessary, but they can be embedded in error messages.
This will hopefully help remove PartialEq from RevsetExpression. Some assertions
are duplicated so that AST->RevsetExpression transformation is covered by tests.
The goal is to remove special case from parsing functions and provide slightly
better error message. I don't know if we'd want to use "all:" in aliases, but
there are no strong reasons to disable it.
This simplifies the interface of helper functions. While revset doesn't have
top-level string pattern or integer literal, these parsing helpers could be
used to parse array subscript or n-th parent operator if any.
This patch copies function rule processing from templater and fileset. Since
function and identifier rules are quite different, it's better to not rely on
the subtle difference between identifier and function_name tokens.
This will allows us to parse "file(..)" arguments as fileset expression by
transforming AST for example. I'm not sure if that's good or bad, but we'll
probably want to embed fileset expressions without quoting.
parse_expression_rule() is split to the first str->ExpressionNode stage and
the second ExpressionNode->RevsetExpression stage. The latter is called
"resolve_*()" in fileset, but we have another "symbol" resolution stage in
revset. So I choose "lower_*()" instead.
parse_function_argument_to_file/string_pattern() functions aren't moved.
They are more like functions that transform parsed tree to intermediate
representation.
I'm planning to rewrite the parser in a similar way to fileset/template parsing,
and the revset_parser module will host functions and types for the first stage.
I haven't started the rewrite, but it seems good to split the revset module
even if we reject the idea.
