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#------------------------------------------------------------------------------
# pycparser: ast_transforms.py
#
# Some utilities used by the parser to create a friendlier AST.
#
# Eli Bendersky [https://eli.thegreenplace.net/]
# License: BSD
#------------------------------------------------------------------------------

from . import c_ast

def fix_switch_cases(switch_node):
    """ The 'case' statements in a 'switch' come out of parsing with one
        child node, so subsequent statements are just tucked to the parent
        Compound. Additionally, consecutive (fall-through) case statements
        come out messy. This is a peculiarity of the C grammar. The following:

switch (myvar) {
                case 10:
                    k = 10;
                    p = k + 1;
                    return 10;
                case 20:
                case 30:
                    return 20;
                default:
                    break;
            }

Creates this tree (pseudo-dump):

Switch
                ID: myvar
                Compound:
                    Case 10:
                        k = 10
                    p = k + 1
                    return 10
                    Case 20:
                        Case 30:
                            return 20
                    Default:
                        break

The goal of this transform is to fix this mess, turning it into the
        following:

Switch
                ID: myvar
                Compound:
                    Case 10:
                        k = 10
                        p = k + 1
                        return 10
                    Case 20:
                    Case 30:
                        return 20
                    Default:
                        break

A fixed AST node is returned. The argument may be modified.
    """
    assert isinstance(switch_node, c_ast.Switch)
    if not isinstance(switch_node.stmt, c_ast.Compound):
        return switch_node

# The new Compound child for the Switch, which will collect children in the
    # correct order
    new_compound = c_ast.Compound([], switch_node.stmt.coord)

# The last Case/Default node
    last_case = None

# Goes over the children of the Compound below the Switch, adding them
    # either directly below new_compound or below the last Case as appropriate
    # (for `switch(cond) {}`, block_items would have been None)
    for child in (switch_node.stmt.block_items or []):
        if isinstance(child, (c_ast.Case, c_ast.Default)):
            # If it's a Case/Default:
            # 1. Add it to the Compound and mark as "last case"
            # 2. If its immediate child is also a Case or Default, promote it
            #    to a sibling.
            new_compound.block_items.append(child)
            _extract_nested_case(child, new_compound.block_items)
            last_case = new_compound.block_items[-1]
        else:
            # Other statements are added as children to the last case, if it
            # exists.
            if last_case is None:
                new_compound.block_items.append(child)
            else:
                last_case.stmts.append(child)

switch_node.stmt = new_compound
    return switch_node

def _extract_nested_case(case_node, stmts_list):
    """ Recursively extract consecutive Case statements that are made nested
        by the parser and add them to the stmts_list.
    """
    if isinstance(case_node.stmts[0], (c_ast.Case, c_ast.Default)):
        stmts_list.append(case_node.stmts.pop())
        _extract_nested_case(stmts_list[-1], stmts_list)

Batal

⬅ site-packages 13 item

Nama	Tipe	Ukuran	Diubah	Perm	Aksi
📁 __pycache__	dir	—	13/09/24 08:06	0755	📂
🐍 __init__.py	py	2.7 KB	04/03/20 21:19	0644	✏️ ⬇
🐍 _ast_gen.py	py	10.4 KB	04/03/20 21:19	0644	✏️ ⬇
🐍 _build_tables.py	py	1 KB	04/03/20 21:19	0644	✏️ ⬇
📄 _c_ast.cfg	cfg	4.1 KB	04/03/20 21:19	0644	✏️ ⬇
🐍 ast_transforms.py	py	3.6 KB	04/03/20 21:19	0644	✏️ ⬇
🐍 c_ast.py	py	29.5 KB	07/04/22 07:13	0644	✏️ ⬇
🐍 c_generator.py	py	15 KB	04/03/20 21:19	0644	✏️ ⬇
🐍 c_lexer.py	py	15.8 KB	07/04/22 07:13	0644	✏️ ⬇
🐍 c_parser.py	py	68.1 KB	07/04/22 07:13	0644	✏️ ⬇
🐍 lextab.py	py	7.1 KB	07/04/22 07:13	0644	✏️ ⬇
🐍 plyparser.py	py	4.8 KB	04/03/20 21:19	0644	✏️ ⬇
🐍 yacctab.py	py	168 KB	07/04/22 07:13	0644	✏️ ⬇

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