255 lines
6.9 KiB
Python
255 lines
6.9 KiB
Python
"""
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Code for parsing the source (python-alike) code
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"""
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from typing import List, Optional, Union, Tuple
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import ast
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from . import wasm
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# pylint: disable=C0103,R0201
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class Visitor:
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"""
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Class to visit a Python syntax tree
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Since we need to visit the whole tree, there's no point in subclassing
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the buildin visitor
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"""
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def visit_Module(self, node: ast.Module) -> wasm.Module:
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"""
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Visits a Python module, which results in a wasm Module
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"""
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assert not node.type_ignores
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module = wasm.Module()
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for stmt in node.body:
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if isinstance(stmt, ast.FunctionDef):
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wnode = self.visit_FunctionDef(stmt)
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if isinstance(wnode, wasm.Import):
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module.imports.append(wnode)
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else:
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module.functions.append(wnode)
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continue
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raise NotImplementedError(stmt)
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return module
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def visit_FunctionDef(self, node: ast.FunctionDef) -> Union[wasm.Import, wasm.Function]:
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"""
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A Python function definition with the @external decorator is returned as import.
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Other functions are returned as (exported) functions.
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"""
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exported = False
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if node.decorator_list:
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assert 1 == len(node.decorator_list)
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decorator = node.decorator_list[0]
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if isinstance(decorator, ast.Name):
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assert 'exported' == decorator.id
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exported = True
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elif isinstance(decorator, ast.Call):
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call = decorator
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assert not node.type_comment
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assert 1 == len(node.body)
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assert isinstance(node.body[0], ast.Expr)
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assert isinstance(node.body[0].value, ast.Ellipsis)
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assert isinstance(call.func, ast.Name)
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assert 'imported' == call.func.id
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assert not call.keywords
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module, name, intname = _parse_import_decorator(node.name, call.args)
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return wasm.Import(module, name, intname, _parse_import_args(node.args))
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result = _parse_annotation(node.returns)
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statements = [
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self.visit_stmt(node, stmt)
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for stmt in node.body
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]
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return wasm.Function(node.name, exported, result, statements)
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def visit_stmt(self, func: ast.FunctionDef, stmt: ast.stmt) -> wasm.Statement:
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"""
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Visits a statement node
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"""
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if isinstance(stmt, ast.Return):
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return self.visit_Return(func, stmt)
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raise NotImplementedError
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def visit_Return(self, func: ast.FunctionDef, stmt: ast.Return) -> wasm.Statement:
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"""
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Visits a statement node
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"""
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assert isinstance(stmt.value, ast.Constant)
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assert isinstance(stmt.value.value, int)
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return_type = _parse_annotation(func.returns)
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return wasm.Statement(
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'{}.const'.format(return_type),
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str(stmt.value.value)
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)
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def _parse_import_decorator(func_name: str, args: List[ast.expr]) -> Tuple[str, str, str]:
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"""
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Parses an @import decorator
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"""
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assert 0 < len(args) < 3
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str_args = [
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arg.value
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for arg in args
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if isinstance(arg, ast.Constant)
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and isinstance(arg.value, str)
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]
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assert len(str_args) == len(args)
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module = str_args.pop(0)
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if str_args:
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name = str_args.pop(0)
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else:
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name = func_name
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return module, name, func_name
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def _parse_import_args(args: ast.arguments) -> List[Tuple[str, str]]:
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"""
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Parses the arguments for an @imported method
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"""
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assert not args.vararg
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assert not args.kwonlyargs
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assert not args.kw_defaults
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assert not args.kwarg
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assert not args.defaults # Maybe support this later on
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arg_list = [
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*args.posonlyargs,
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*args.args,
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]
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return [
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(arg.arg, _parse_annotation(arg.annotation))
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for arg in arg_list
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]
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def _parse_annotation(ann: Optional[ast.expr]) -> str:
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"""
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Parses a typing annotation
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"""
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assert ann is not None, 'Web Assembly requires type annotations'
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assert isinstance(ann, ast.Name)
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result = ann.id
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assert result in ['i32']
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return result
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# def visit_ImportFrom(self, node):
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# for alias in node.names:
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# self.imports.append(Import(
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# node.module,
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# alias.name,
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# alias.asname,
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# ))
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#
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# def generic_visit(self, node: Any) -> None:
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# print(node)
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# super().generic_visit(node)
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#
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# def visit_FunctionDef(self, node: ast.FunctionDef) -> None:
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# is_export = False
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#
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# if node.decorator_list:
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# assert 1 == len(node.decorator_list)
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#
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# call = node.decorator_list[0]
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# if not isinstance(call, ast.Name):
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# assert isinstance(call, ast.Call)
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#
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# assert 'external' == call.func.id
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# assert 1 == len(call.args)
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# assert isinstance(call.args[0].value, str)
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#
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# import_ = Import(
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# call.args[0].value,
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# node.name,
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# node.name,
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# )
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#
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# import_.params = [
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# arg.annotation.id
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# for arg in node.args.args
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# ]
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#
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# self.module.imports.append(import_)
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# return
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#
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# assert call.id == 'export'
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# is_export = True
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#
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# func = Function(
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# node.name,
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# is_export,
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# )
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#
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# for arg in node.args.args:
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# func.params.append(
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# (arg.arg, arg.annotation.id)
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# )
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# func.result = node.returns
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#
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# self._stack.append(func)
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# self.generic_visit(node)
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# self._stack.pop()
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#
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# self.module.functions.append(func)
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#
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# def visit_Call(self, node: ast.Call) -> None:
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# self.generic_visit(node)
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#
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# func = self._stack[-1]
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# func.statements.append(
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# Statement('call', '$' + node.func.id)
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# )
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#
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# def visit_BinOp(self, node: ast.BinOp) -> None:
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# self.generic_visit(node)
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#
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# func = self._stack[-1]
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#
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# if 'Add' == node.op.__class__.__name__:
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# func.statements.append(
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# Statement('i32.add')
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# )
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# elif 'Mult' == node.op.__class__.__name__:
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# func.statements.append(
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# Statement('i32.mul')
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# )
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# else:
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# raise NotImplementedError
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#
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# def visit_Constant(self, node: ast.Constant) -> None:
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# func = self._stack[-1]
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# if isinstance(node.value, int):
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# func.statements.append(
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# Statement('i32.const', str(node.value))
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# )
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#
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# self.generic_visit(node)
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