Add parser backtracking #25
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Port V1
Functionality that still needs to ported from the the old Spicy research prototype
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bbannier
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marked this issue as related to #118 |
rsmmr
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Dec 2, 2020
If a field is marked with ``&try``, a later call to ``self.backtrack()``
anywhere down in the parse tree will return to that position and
continue there. (This is ported over the old prototype).
Example:
export type test = unit {
a: bytes &length=4;
foo: Foo &try;
bar: Bar;
b: bytes &length=6;
on %done { print self; }
};
type Foo = unit {
a: int8 { print "Foo.a", self; }
b: int8 { print "Backtracking"; self.backtrack(); }
c: int8 { print "Foo.c", self; }
};
type Bar = unit {
a: int8 { print "Bar.a", self; }
b: int8 { print "Bar.b", self; }
c: int8 { print "Bar.c", self; }
};
# printf '1234\001\002\003567890' | pac-driver backtrack.pac2
Foo.a <a=1, b=(not set), c=(not set)>
Backtracking
Bar.a <a=1, b=(not set), c=(not set)>
Bar.b <a=1, b=2, c=(not set)>
Bar.c <a=1, b=2, c=3>
<a=1234, foo=(Null), bar=<a=1, b=2, c=3>, b=567890>
Closes #25.
rsmmr
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Dec 8, 2020
If a field is marked with ``&try``, a later call to ``self.backtrack()``
anywhere down in the parse tree will return to that position and
continue there. (This is ported over the old prototype).
Example:
export type test = unit {
a: bytes &length=4;
foo: Foo &try;
bar: Bar;
b: bytes &length=6;
on %done { print self; }
};
type Foo = unit {
a: int8 { print "Foo.a", self; }
b: int8 { print "Backtracking"; self.backtrack(); }
c: int8 { print "Foo.c", self; }
};
type Bar = unit {
a: int8 { print "Bar.a", self; }
b: int8 { print "Bar.b", self; }
c: int8 { print "Bar.c", self; }
};
# printf '1234\001\002\003567890' | pac-driver backtrack.pac2
Foo.a <a=1, b=(not set), c=(not set)>
Backtracking
Bar.a <a=1, b=(not set), c=(not set)>
Bar.b <a=1, b=2, c=(not set)>
Bar.c <a=1, b=2, c=3>
<a=1234, foo=(Null), bar=<a=1, b=2, c=3>, b=567890>
Closes #25.
rsmmr
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Dec 10, 2020
* origin/topic/robin/gh-25-backtrack: Fix Sphinx helper script that emits command lines. Add support for manual backtracking to Spicy. Support &eod for vector parsing.
rsmmr
added a commit
that referenced
this issue
Dec 10, 2020
* origin/topic/robin/gh-25-backtrack: Fix Sphinx helper script that emits command lines. Add support for manual backtracking to Spicy. Support &eod for vector parsing.
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Parse attributes:
&tryUnit methods
backtrackNote: Make sure backtracking from an
%errorhook continues parsing.Old tests in
backtrack*in https://github.com/rsmmr/hilti/tree/master/tests/spicy/unitThe text was updated successfully, but these errors were encountered: