If no infix action is defined, a suffix action isn't ambiguous, so it should
be taken no matter if the next token can be an operand. This is exactly the
same flow as prefix/primary handling.
This change has no effect now because all suffix tokens have infix actions.
If both actions are defined, a primary-expression action is accepted only if
the next token never starts new term. For example,
parsed as primary expression:
":" # next token 'end' has no action
"(:)" # next token ')' has no action
":+y" # next token '+' is infix operator
parsed as prefix operator:
":y" # next token 'y' is primary expression
":-y" # next token '-' is prefix operator
This is mostly the same resolution as the infix/suffix rules.
This will allow us to define both a primary expression, ":", and a prefix
operator, ":y". The ambiguity will be resolved by the next patch.
Prefix actions in elements table are adjusted as follows:
original prefix primary prefix
----------------- -------- -----------------
("group", 1, ")") -> n/a ("group", 1, ")")
("negate", 19) -> n/a ("negate", 19)
("symbol",) -> "symbol" n/a
Future patches will separate primary expression and prefix operator actions.
This function will be used to resolve ambiguity of them.
This is a step to remove the old-style revexpr parser. We need both ":" and
":y" operators for backward compatibility.
Keyword arguments will be convenient for functions that will take more than
one optional or boolean flags. For example,
file(pattern[, subrepos=false])
subrepo([[pattern], status])
Because I don't think all functions should accept key=value syntax, getkwargs()
does not support variadic functions such as 'ancestor(*changeset)'.
The core logic is placed in the parser module because keyword arguments will
be more useful in the templater, where functions take more options. Test cases
will be added by the next patch.
This can simplify the interface of parse() function. Our tokenizer tends to
have optional arguments other than the message to be parsed.
Before this patch, the "lookup" argument existed only for the revset, and the
templater had to pack [program, start, end] to be passed to its tokenizer.
This get rid of another StopIteration abomination. The change in self.current
value is supposed to not matter as nobody should be calling '_advance' after
that (as per Matt wisdom).
