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"""Data structure extracted from parsing the EDSL which are added within the
Rust code."""
from __future__ import annotations
# mypy: disallow-untyped-defs, disallow-incomplete-defs, disallow-untyped-calls
import typing
import os
from dataclasses import dataclass
from .utils import keep_until
from .grammar import Element, Grammar, LenientNt, NtDef, Production
@dataclass(frozen=True)
class ImplFor:
__slots__ = ['param', 'trait', 'for_type']
param: str
trait: str
for_type: str
def eq_productions(grammar: Grammar, prod1: Production, prod2: Production) -> bool:
s1 = tuple(e for e in prod1.body if grammar.is_shifted_element(e))
s2 = tuple(e for e in prod2.body if grammar.is_shifted_element(e))
return s1 == s2
def merge_productions(grammar: Grammar, prod1: Production, prod2: Production) -> Production:
# Consider all shifted elements as non-moveable elements, and insert other
# around these.
assert eq_productions(grammar, prod1, prod2)
l1 = list(prod1.body)
l2 = list(prod2.body)
body: typing.List[Element] = []
while l1 != [] and l2 != []:
front1 = list(keep_until(l1, grammar.is_shifted_element))
front2 = list(keep_until(l2, grammar.is_shifted_element))
assert front1[-1] == front2[-1]
l1 = l1[len(front1):]
l2 = l2[len(front2):]
if len(front1) == 1:
body = body + front2
elif len(front2) == 1:
body = body + front1
else:
raise ValueError("We do not know how to sort operations yet.")
return prod1.copy_with(body=body)
@dataclass(frozen=True)
class ExtPatch:
"Patch an existing grammar rule by adding Code"
prod: typing.Tuple[LenientNt, str, NtDef]
def apply_patch(
self,
filename: os.PathLike,
grammar: Grammar,
nonterminals: typing.Dict[LenientNt, NtDef]
) -> None:
# - name: non-terminal.
# - namespace: ":" for syntactic or "::" for lexical. Always ":" as
# defined by rust_nt_def.
# - nt_def: A single non-terminal definition with a single production.
(name, namespace, nt_def) = self.prod
gnt_def = nonterminals[name]
# Find a matching production in the grammar.
assert nt_def.params == gnt_def.params
new_rhs_list = []
assert len(nt_def.rhs_list) == 1
patch_prod = nt_def.rhs_list[0]
applied = False
for grammar_prod in gnt_def.rhs_list:
if eq_productions(grammar, grammar_prod, patch_prod):
grammar_prod = merge_productions(grammar, grammar_prod, patch_prod)
applied = True
new_rhs_list.append(grammar_prod)
if not applied:
raise ValueError("{}: Unable to find a matching production for {} in the grammar:\n {}"
.format(filename, name, grammar.production_to_str(name, patch_prod)))
result = gnt_def.with_rhs_list(new_rhs_list)
nonterminals[name] = result
@dataclass
class GrammarExtension:
"""A collection of grammar extensions, with added code, added traits for the
action functions.
"""
target: None
grammar: typing.List[ExtPatch]
filename: os.PathLike
def apply_patch(
self,
grammar: Grammar,
nonterminals: typing.Dict[LenientNt, NtDef]
) -> None:
# A grammar extension is composed of multiple production patches.
for ext in self.grammar:
if isinstance(ext, ExtPatch):
ext.apply_patch(self.filename, grammar, nonterminals)
else:
raise ValueError("Extension of type {} not yet supported.".format(ext.__class__))
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