1 files changed, 192 insertions, 0 deletions
diff --git a/libmisc/wrap-cc b/libmisc/wrap-cc
index e7a0b91..f8d58c5 100755
--- a/libmisc/wrap-cc
+++ b/libmisc/wrap-cc
@@ -5,6 +5,7 @@
 # SPDX-License-Identifier: AGPL-3.0-or-later
 
 import os
+import re
 import subprocess
 import sys
 import typing
@@ -175,6 +176,197 @@ def preprocess(all_args: list[str]) -> typing.NoReturn:
     os.execvp(arg0, [arg0, *common_flags, *output_flags, infile])
 
 
+def cpp_squash_linemarkers(text: str) -> str:
+    out = ""
+    buf_marker = ""
+    buf_body = ""
+    for line in text.splitlines(keepends=True):
+        if line.startswith("# "):
+            if buf_marker != line or buf_body.strip():
+                out += buf_marker
+            if buf_body.strip():
+                out += buf_body
+            buf_marker = line
+            buf_body = ""
+        else:
+            buf_body += line
+    if buf_body.strip():
+        out += buf_marker
+        out += buf_body
+    return out
+
+
+class Preprocessor:
+    _cpp: list[str]
+    _builtin_defines: list[str] | None = None
+
+    def __init__(self, cpp: list[str]) -> None:
+        self._cpp = cpp
+        self._builtin_defines = None
+
+    @property
+    def builtin_defines(self) -> list[str]:
+        if self._builtin_defines is None:
+            self._builtin_defines = subprocess.run(
+                [*self._cpp, "-quiet", "-undef", "-nostdinc", "-dM"],
+                stdin=subprocess.DEVNULL,
+                stdout=subprocess.PIPE,
+                stderr=sys.stderr,
+                check=True,
+                text=True,
+            ).stdout.splitlines(keepends=True)
+        return self._builtin_defines
+
+    def process_file(self, infile: str, flags: list[str]) -> str:
+        # First/main preprocessor pass.
+        text = subprocess.run(
+            [*self._cpp, "-dD", *flags, infile],
+            stdin=subprocess.DEVNULL,
+            stdout=subprocess.PIPE,
+            stderr=sys.stderr,
+            check=True,
+            text=True,
+        ).stdout
+
+        # Extra (subclass) processing.
+        text = self.extra(text)
+
+        # Split the combined "-dD" output into "-dM" output and normal
+        # output.
+        macro_text = ""
+        normal_text = ""
+        for line in text.splitlines(keepends=True):
+            if line.startswith("#define ") or line.startswith("#undef "):
+                macro_text += line
+                normal_text += "\n"
+            else:
+                normal_text += line
+        return normal_text
+
+    def process_fragment(self, before: str, text: str) -> str:
+        before_lines = before.splitlines(keepends=True)
+        builtin_defines = self.builtin_defines
+        prefix = "".join(
+            [
+                line
+                for line in before_lines
+                if line.startswith("#") and line not in builtin_defines
+            ]
+        )
+        prefix = cpp_squash_linemarkers(prefix)
+
+        text = subprocess.run(
+            [
+                *self._cpp,
+                "-quiet",
+                "-undef",
+                "-nostdinc",
+                "-dD",
+            ],
+            input=prefix + text,
+            stdout=subprocess.PIPE,
+            stderr=sys.stderr,
+            check=True,
+            text=True,
+        ).stdout
+
+        text = cpp_squash_linemarkers(text)
+        text = text[text.index(prefix) + len(prefix) :]
+
+        if text.startswith("# "):
+            text = "\n" + text
+
+        text = self.extra(text)
+
+        return text
+
+    def extra(self, text: str) -> str:
+        return text
+
+
+################################################################################
+
+
+class EnhancedPreprocessor(Preprocessor):
+    def process_file(self, infile: str, flags: list[str]) -> str:
+        return super().process_file(infile, ["-D__LIBMISC_ENHANCED_CPP__", *flags])
+
+    special_macros = [
+        "LM_EVAL",
+        "LM_FOREACH_PARAM",
+        "LM_FOREACH_TUPLE",
+    ]
+    re_special = re.compile(
+        r"__xx_(?P<macro>"
+        + "|".join([re.escape(m) for m in special_macros])
+        + r")_xx__\("
+    )
+
+    def extra(self, text: str) -> str:
+        pos = 0
+        while intro := self.re_special.search(text, pos):
+            nl = text.rfind("\n", 0, intro.start())
+            if text[nl + 1] == "#":
+                pos = intro.end()
+                continue
+
+            macro = intro.group("macro")
+            args: list[str] = []
+
+            def add_arg(arg: str) -> None:
+                args.append(arg)
+
+            beg_paren = intro.end() - 1
+            end_paren = cpp_scan_tuple(text, beg_paren, add_arg)
+
+            before = text[: intro.start()]
+            # old = text[intro.start() : end_paren + 1]
+            after = text[end_paren + 1 :]
+
+            new = self._eval_macro(before, macro, args)
+
+            text = before + new + after
+            pos = len(before) + len(new)
+        return text
+
+    def _eval_macro(self, before: str, macro: str, args: list[str]) -> str:
+        match macro:
+            case "LM_EVAL":  # LM_EVAL(...)
+                ret = ",".join(args)
+                while True:
+                    ret2 = self.process_fragment(before, ret)
+                    if ret2 == ret:
+                        break
+                    ret = ret2
+                return ret
+            case "LM_FOREACH_PARAM":  # LM_FOREACH_PARAM(func, (fixedparams), params...)
+                assert len(args) >= 2
+                func = args[0].strip()
+                fixedparams = args[1].strip()[1:-1].strip()
+                if fixedparams:
+                    fixedparams += ", "
+                ret = ""
+                for param in args[2:]:
+                    ret += f"{func}({fixedparams}{param})"
+                return ret
+            case "LM_FOREACH_TUPLE":  # LM_FOREACH_TUPLE(tuples, func, fixedparams...)
+                tuples_str = args[0].lstrip()
+                func = args[1].strip()
+                fixedparams = "".join([a.strip() + ", " for a in args[2:]])
+                ret = ""
+                while tuples_str:
+                    end_paren = cpp_scan_tuple(tuples_str, 0)
+                    tup = tuples_str[1:end_paren]
+                    ret += f"{func}({fixedparams}{tup})"
+                    tuples_str = tuples_str[end_paren + 1 :].lstrip()
+                return ret
+            case _:
+                raise ValueError(f"unknown macro: {macro}")
+
+
+################################################################################
+
+
 def main(all_args: list[str]) -> typing.NoReturn:
     if len(all_args) >= 2 and all_args[0].endswith("cc1") and all_args[1] == "-E":
         preprocess(all_args)