112 lines
4.3 KiB
Python
112 lines
4.3 KiB
Python
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import ast
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import copy
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from helper import *
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from type_def import *
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from inference import *
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from parse_expr import parse_expr
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def parse_stmts(ctx: Context,
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sym_table: dict[str, Type],
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used_sym_table: dict[str, Type],
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nodes):
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sym_table2 = copy.copy(sym_table)
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used_sym_table2 = copy.copy(used_sym_table)
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for node in nodes:
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if isinstance(node, ast.Assign):
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a, b, returned = parse_assign(ctx, sym_table2, used_sym_table2, node)
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elif isinstance(node, ast.If):
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a, b, returned = parse_if_stmt(ctx, sym_table2, used_sym_table2, node)
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else:
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raise CustomError(f'{node} is not supported yet')
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sym_table2 |= a
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used_sym_table2 |= b
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if returned:
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return sym_table2, used_sym_table2, True
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return sym_table2, used_sym_table2, False
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def get_target_type(ctx: Context,
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sym_table: dict[str, Type],
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used_sym_table: dict[str, Type],
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target):
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if isinstance(target, ast.Subscript):
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t = get_target_type(ctx, sym_table, used_sym_table, target.value)
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if not isinstance(t, ListType):
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raise CustomError(f'cannot index through type {t}')
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if isinstance(target.slice, ast.Slice):
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raise CustomError(f'assignment to slice is not supported')
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i = parse_expr(ctx, sym_table, target.slice)
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if i != ctx.types['int32']:
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raise CustomError(f'index must be int32')
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return t.params[0]
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elif isinstance(target, ast.Attribute):
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t = get_target_type(ctx, sym_table, used_sym_table, target.value)
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if target.attr not in t.fields:
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raise CustomError(f'{t} has no field {target.attr}')
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return t.fields[target.attr]
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elif isinstance(target, ast.Name):
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if target.id not in sym_table:
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raise CustomError(f'unbounded {target.id}')
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return sym_table[target.id]
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else:
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raise CustomError(f'assignment to {target} is not supported')
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def parse_binding(ctx: Context,
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sym_table: dict[str, Type],
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used_sym_table: dict[str, Type],
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target,
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ty):
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if isinstance(target, ast.Name):
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if target.id in used_sym_table:
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if used_sym_table[target.id] != ty:
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raise CustomError('inconsistent type')
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if target.id == '_':
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return {}
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return {target.id: ty}
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elif isinstance(target, ast.Tuple):
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if not isinstance(ty, TupleType):
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raise CustomError(f'cannot pattern match over {ty}')
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if len(target.elts) != len(ty.params):
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raise CustomError(f'pattern matching length mismatch')
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result = {}
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for x, y in zip(target.elts, ty.params):
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new = parse_binding(ctx, sym_table, used_sym_table, x, y)
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old_len = len(result)
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result |= new
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used_sym_table |= new
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if len(result) != old_len + len(new):
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raise CustomError(f'variable name clash')
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return result
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else:
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t = get_target_type(ctx, sym_table, used_sym_table, target)
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if ty != t:
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raise CustomError(f'inconsistent type')
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return {}
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def parse_assign(ctx: Context,
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sym_table: dict[str, Type],
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used_sym_table: dict[str, Type],
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node):
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# permitted assignment targets:
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# variables, class fields, list elements
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# function evaluation is only allowed within list index
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# may relax later after when we settle on lifetime handling
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ty = parse_expr(ctx, sym_table, node.value)
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results = {}
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for target in node.targets:
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results |= parse_binding(ctx, sym_table, used_sym_table, target, ty)
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return results, results, False
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def parse_if_stmt(ctx: Context,
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sym_table: dict[str, Type],
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used_sym_table: dict[str, Type],
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node):
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test = parse_expr(ctx, sym_table, node.test)
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if test != ctx.types['bool']:
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raise CustomError(f'condition must be bool instead of {test}')
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a, b, r = parse_stmts(ctx, sym_table, used_sym_table, node.body)
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used_sym_table |= b
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a1, b1, r1 = parse_stmts(ctx, sym_table, used_sym_table, node.orelse)
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defined = {k: a[k] for k in a if k in a1}
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return defined, b | b1, r and r1
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