GH-111485: Separate out parsing, analysis and code-gen phases of tier 1 code generator (GH-112299)

Tools/cases_generator/parser.py

@@ -0,0 +1,55 @@
+from parsing import (
+    InstDef,
+    Macro,
+    Pseudo,
+    Family,
+    Parser,
+    Context,
+    CacheEffect,
+    StackEffect,
+    OpName,
+    AstNode,
+)
+from formatting import prettify_filename
+
+
+BEGIN_MARKER = "// BEGIN BYTECODES //"
+END_MARKER = "// END BYTECODES //"
+
+
+def parse_files(filenames: list[str]) -> list[AstNode]:
+    result: list[AstNode] = []
+    for filename in filenames:
+        with open(filename) as file:
+            src = file.read()
+
+        psr = Parser(src, filename=prettify_filename(filename))
+
+        # Skip until begin marker
+        while tkn := psr.next(raw=True):
+            if tkn.text == BEGIN_MARKER:
+                break
+        else:
+            raise psr.make_syntax_error(
+                f"Couldn't find {BEGIN_MARKER!r} in {psr.filename}"
+            )
+        start = psr.getpos()
+
+        # Find end marker, then delete everything after it
+        while tkn := psr.next(raw=True):
+            if tkn.text == END_MARKER:
+                break
+        del psr.tokens[psr.getpos() - 1 :]
+
+        # Parse from start
+        psr.setpos(start)
+        thing_first_token = psr.peek()
+        while node := psr.definition():
+            assert node is not None
+            result.append(node)  # type: ignore[arg-type]
+        if not psr.eof():
+            psr.backup()
+            raise psr.make_syntax_error(
+                f"Extra stuff at the end of {filename}", psr.next(True)
+            )
+    return result