nx_post_support/server/src/tools/def_symbols.py

"""Block templates, addresses and formats declared in NX post definition (.def) files."""

import re
from dataclasses import dataclass
from pathlib import Path

BLOCK_TEMPLATE = "block_template"
ADDRESS = "address"
FORMAT = "format"

_KINDS = {"BLOCK_TEMPLATE": BLOCK_TEMPLATE, "ADDRESS": ADDRESS, "FORMAT": FORMAT}
_HEADER_RE = re.compile(r"^\s*(BLOCK_TEMPLATE|ADDRESS|FORMAT)\s+([^\s{]+)")
# A block template element is an address followed by its expression: X[$mom_pos(0)].
_ELEMENT_RE = re.compile(r"^\s*([A-Za-z_]\w*)\[")
_PROPERTY_RE = re.compile(r"^\s*([A-Za-z_]+)\s*(.*?)\s*$")


@dataclass(frozen=True)
class DefDeclaration:
    kind: str
    name: str
    # 0-based line and UTF-16 columns of the name.
    line: int
    start: int
    end: int
    end_line: int
    text: str
    # ADDRESS: body properties such as ("LEADER", '"X"'); FORMAT: (("FORMAT", '"%d"'),).
    properties: tuple[tuple[str, str], ...] = ()


@dataclass(frozen=True)
class DefReference:
    """An address used as element of a block template."""

    kind: str
    name: str
    line: int
    start: int
    end: int
    container: str


@dataclass(frozen=True)
class DefDocument:
    declarations: tuple[DefDeclaration, ...] = ()
    references: tuple[DefReference, ...] = ()

    def names(self, kind: str) -> tuple[str, ...]:
        return tuple(dict.fromkeys(item.name for item in self.declarations if item.kind == kind))


@dataclass(frozen=True)
class DefSymbols:
    block_templates: tuple[str, ...] = ()
    addresses: tuple[str, ...] = ()


def _utf16_length(text: str) -> int:
    return len(text.encode("utf-16-le")) // 2


def _is_comment(line: str) -> bool:
    return line.lstrip().startswith("#")


def _body(lines: list[str], header: int, rest: str) -> tuple[int, int, int] | None:
    """Return (first body line, first body column, closing line) of a braced body.

    The body starts after the first "{" on the header line or on a following
    line and ends at the next line starting with "}".
    """
    if "{" in rest:
        after = rest.split("{", 1)[1]
        if "}" in after:
            return None
        start = header + 1
    else:
        start = header + 1
        while start < len(lines) and (not lines[start].strip() or _is_comment(lines[start])):
            start += 1
        if start >= len(lines) or not lines[start].lstrip().startswith("{"):
            return None
        start += 1
    end = start
    while end < len(lines) and not lines[end].lstrip().startswith("}"):
        end += 1
    return start, 0, min(end, len(lines) - 1)


def parse_def_document(source: str) -> DefDocument:
    """Parse the block templates, addresses and formats of a .def source."""
    lines = source.splitlines()
    declarations: list[DefDeclaration] = []
    references: list[DefReference] = []
    index = 0
    while index < len(lines):
        line = lines[index]
        match = None if _is_comment(line) else _HEADER_RE.match(line)
        if match is None:
            index += 1
            continue

        kind = _KINDS[match.group(1)]
        name = match.group(2)
        start = _utf16_length(line[: match.start(2)])
        end = start + _utf16_length(name)
        rest = line[match.end(2) :]

        if kind == FORMAT:
            declarations.append(
                DefDeclaration(kind, name, index, start, end, index, line.strip(), (("FORMAT", rest.strip()),))
            )
            index += 1
            continue

        body = _body(lines, index, rest)
        end_line = index if body is None else body[2]
        properties: list[tuple[str, str]] = []
        if body is not None:
            for number in range(body[0], body[2]):
                body_line = lines[number]
                if _is_comment(body_line) or not body_line.strip():
                    continue
                if kind == BLOCK_TEMPLATE:
                    element = _ELEMENT_RE.match(body_line)
                    if element is not None:
                        element_start = _utf16_length(body_line[: element.start(1)])
                        references.append(
                            DefReference(
                                ADDRESS,
                                element.group(1),
                                number,
                                element_start,
                                element_start + _utf16_length(element.group(1)),
                                name,
                            )
                        )
                else:
                    prop = _PROPERTY_RE.match(body_line)
                    if prop is not None:
                        properties.append((prop.group(1).upper(), prop.group(2)))

        declarations.append(
            DefDeclaration(
                kind,
                name,
                index,
                start,
                end,
                end_line,
                "\n".join(lines[index : end_line + 1]),
                tuple(properties),
            )
        )
        index = end_line + 1

    return DefDocument(tuple(declarations), tuple(references))


def parse_def_symbols(source: str) -> DefSymbols:
    """Return the BLOCK_TEMPLATE and ADDRESS names of a .def source in declaration order."""
    document = parse_def_document(source)
    return DefSymbols(
        block_templates=document.names(BLOCK_TEMPLATE),
        addresses=document.names(ADDRESS),
    )


def read_def_source(path: Path) -> str:
    data = path.read_bytes()
    try:
        return data.decode("utf-8-sig")
    except UnicodeDecodeError:
        # Older Windows NX layers use the ANSI code page.
        return data.decode("cp1252")


def read_def_symbols(path: Path) -> DefSymbols:
    return parse_def_symbols(read_def_source(path))