class Sthx::Ahead
- Sthx::Ahead
- Reference
- Object
Overview
Forward declaration of a rule.
Included Modules
Defined in:
synthax/rule.crConstructors
Instance Method Summary
-
#advance(cursor : Cursor, data : TreeData, *, collect : Collect) : Advance::Result
Performs cursor motion and returns the result, one of
Advance::Result
: successAdvance::Ok
or failureAdvance::Err
. -
#put(rule : Rule) : self
Assigns rule, should be called when its definition becomes available.
Instance methods inherited from module Sthx::Rule
advance(cursor : Cursor, data : TreeData, *, collect : Collect) : Advance::Result
advance,
apply(source : String, *, offset : Int = 0, exact : Bool = true, root : String = "root") : Apply::Result
apply,
apply!(source : String, **kwargs)
apply!,
apply?(source : String, **kwargs)
apply?
Constructor Detail
Instance Method Detail
Performs cursor motion and returns the result, one of Advance::Result
:
success Advance::Ok
or failure Advance::Err
.
data is the TreeData
object built so far.
To implementors of this method: in case of failure to commit, cursor
must be rolled back to its state before calling this method. In other
words, #advance
is implemented in a "transaction" kind of way. Intermediate
results and changes must never be available to the caller. This method either
succeeds and mutates the cursor; or it fails and leaves the cursor intact.
Assigns rule, should be called when its definition becomes available.
expr = ahead
expr.put('(' & maybe(expr) & ')')
expr.apply?("(((())))") # => Tree
expr.apply?("((())") # => nil