struct Sthx::FirstOf

Overview

Branch. The first rule to succeed wins. This is obviously order dependent. The order is exactly that with which this rule was initialized. So e.g. given "x" | "xx" and source string "xx" the rule "x" will always match and "xx" will be essentially unreachable.

The faster option between FirstOf and LongestOf.

Included Modules

Defined in:

synthax/rule.cr

Instance Method Summary

Instance methods inherited from module Sthx::RuleCollection

with(rule : Rule) : self with

Constructor methods inherited from module Sthx::RuleCollection

new(rules : Array(Rule)) new

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?

Instance Method Detail

def advance(cursor : Cursor, data : TreeData, *, collect : Collect) : Advance::Result #
Description copied from module Sthx::Rule

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.


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