Add handling for #if macros. Work in progress

python · markshannon · Apr 2, 2025 · Mar 28, 2025 · Mar 30, 2025 · Mar 31, 2025
commit f7cccf8bba58c02e941beae9530cfac84d56d27f
@@ -99,7 +99,7 @@ def emit_token(self, tkn: Token) -> None:
         self.maybe_dedent(tkn.text)
         self.set_position(tkn)
         self.emit_text(tkn.text)
-        if tkn.kind == "CMACRO":
+        if tkn.kind.startswith("CMACRO"):
             self.newline = True
         self.maybe_indent(tkn.text)
 

@@ -12,7 +12,7 @@
 from typing import Callable, TextIO, Iterator, Iterable
 from lexer import Token
 from stack import Storage, StackError
-from parser import Stmt, SimpleStmt, BlockStmt, IfStmt, ForStmt, WhileStmt
+from parser import Stmt, SimpleStmt, BlockStmt, IfStmt, ForStmt, WhileStmt, MacroIfStmt
 
 # Set this to true for voluminous output showing state of stack and locals
 PRINT_STACKS = False
@@ -476,6 +476,8 @@ def _emit_stmt(
             return self._emit_for(stmt, uop, storage, inst)
         elif isinstance(stmt, WhileStmt):
             return self._emit_while(stmt, uop, storage, inst)
+        elif isinstance(stmt, MacroIfStmt):
+            return self._emit_macro_if(stmt, uop, storage, inst)
         else:
             raise NotImplementedError("Unexpected statement")
 
@@ -533,6 +535,37 @@ def _emit_simple(
         except StackError as ex:
             raise analysis_error(ex.args[0], tkn) #from None
 
+
+    def _emit_macro_if(
+        self,
+        stmt: IfStmt,
+        uop: CodeSection,
+        storage: Storage,
+        inst: Instruction | None,
+    ) -> tuple[bool, Token, Storage]:
+        self.out.emit(stmt.condition)
+        branch = stmt.else_ is not None
+        reachable = True
+        for s in stmt.body:
+            r, tkn, storage = self._emit_stmt(s, uop, storage, inst)
+            if tkn is not None:
+                self.out.emit(tkn)
+            if not r:
+                reachable = False
+        if branch:
+            else_storage = storage.copy()
+            self.out.emit(stmt.else_)
+            for s in stmt.else_body:
+                r, tkn, else_storage = self._emit_stmt(s, uop, else_storage, inst)
+                if tkn is not None:
+                    self.out.emit(tkn)
+                if not r:
+                    reachable = False
+            storage.merge(else_storage, self.out)
+        self.out.emit(stmt.endif)
+        return reachable, None, storage
+
+
     def _emit_if(
         self,
         stmt: IfStmt,
@@ -640,7 +673,7 @@ def emit_tokens(
             if emit_braces:
                 self.out.emit(tkn)
         except StackError as ex:
-            raise analysis_error(ex.args[0], last) from None
+            raise analysis_error(ex.args[0], tkn) from None
         return storage
 
     def emit(self, txt: str | Token) -> None:

@@ -80,7 +80,10 @@ def choice(*opts: str) -> str:
 
 # Macros
 macro = r"#.*\n"
-CMACRO = "CMACRO"
+CMACRO_IF = "CMACRO_IF"
+CMACRO_ELSE = "CMACRO_ELSE"
+CMACRO_ENDIF = "CMACRO_ENDIF"
+CMACRO_OTHER = "CMACRO_OTHER"
 
 id_re = r"[a-zA-Z_][0-9a-zA-Z_]*"
 IDENTIFIER = "IDENTIFIER"
@@ -292,6 +295,7 @@ def tokenize(src: str, line: int = 1, filename: str = "") -> Iterator[Token]:
     linestart = -1
     for m in matcher.finditer(src):
         start, end = m.span()
+        macro_body = ""
         text = m.group(0)
         if text in keywords:
             kind = keywords[text]
@@ -316,7 +320,15 @@ def tokenize(src: str, line: int = 1, filename: str = "") -> Iterator[Token]:
         elif text[0] == "'":
             kind = CHARACTER
         elif text[0] == "#":
-            kind = CMACRO
+            macro_body = text[1:].strip()
+            if macro_body.startswith("if"):
+                kind = CMACRO_IF
+            elif macro_body.startswith("else"):
+                kind = CMACRO_ELSE
+            elif macro_body.startswith("endif"):
+                kind = CMACRO_ENDIF
+            else:
+                kind = CMACRO_OTHER
         elif text[0] == "/" and text[1] in "/*":
             kind = COMMENT
         else:
@@ -338,7 +350,7 @@ def tokenize(src: str, line: int = 1, filename: str = "") -> Iterator[Token]:
                 line += newlines
         else:
             begin = line, start - linestart
-            if kind == CMACRO:
+            if macro_body:
                 linestart = end
                 line += 1
         if kind != "\n":

@@ -17,6 +17,7 @@
     ForStmt,
     WhileStmt,
     BlockStmt,
+    MacroIfStmt,
 )
 
 import pprint

@@ -171,7 +171,9 @@ def tokens(self) -> Iterator[lx.Token]:
 class MacroIfStmt(Stmt):
     condition: lx.Token
     body: list[Stmt]
+    else_: lx.Token | None
     else_body: list[Stmt] | None
+    endif: lx.Token
 
     def print(self, out:CWriter) -> None:
         out.emit(self.condition)
@@ -657,7 +659,15 @@ def stmt(self) -> Stmt:
             return self.for_stmt(tkn)
         elif tkn := self.expect(lx.WHILE):
             return self.while_stmt(tkn)
-        elif tkn := self.expect(lx.CMACRO):
+        elif tkn := self.expect(lx.CMACRO_IF):
+            return self.macro_if(tkn)
+        elif tkn := self.expect(lx.CMACRO_ELSE):
+            msg = "Unexpected #else"
+            raise self.make_syntax_error(msg)
+        elif tkn := self.expect(lx.CMACRO_ENDIF):
+            msg = "Unexpected #endif"
+            raise self.make_syntax_error(msg)
+        elif tkn := self.expect(lx.CMACRO_OTHER):
             return SimpleStmt([tkn])
         elif tkn := self.expect(lx.SWITCH):
             msg = "switch statements are not supported due to their complex flow control. Sorry."
@@ -678,6 +688,24 @@ def if_stmt(self, if_: lx.Token) -> IfStmt:
                 else_body = self.block()
         return IfStmt(if_, condition, body, else_, else_body)
 
+
+    def macro_if(self, cond: lx.Token) -> IfStmt:
+        else_ = None
+        body: list[Stmt] = []
+        else_body: list[Stmt] | None = None
+        part = body
+        while True:
+            if tkn := self.expect(lx.CMACRO_ENDIF):
+                return MacroIfStmt(cond, body, else_, else_body, tkn)
+            elif tkn := self.expect(lx.CMACRO_ELSE):
+                if part is else_body:
+                    raise self.make_syntax_error("Multiple #else")
+                else_ = tkn
+                else_body = []
+                part = else_body
+            else:
+                part.append(self.stmt())
+
     def for_stmt(self, for_: lx.Token) -> ForStmt:
         lparen = self.require(lx.LPAREN)
         header = [lparen] + self.consume_to(lx.RPAREN)
@@ -693,6 +721,7 @@ def while_stmt(self, while_: lx.Token) -> WhileStmt:
 
 if __name__ == "__main__":
     import sys
+    import pprint
 
     if sys.argv[1:]:
         filename = sys.argv[1]
@@ -710,5 +739,5 @@ def while_stmt(self, while_: lx.Token) -> WhileStmt:
         filename = "<default>"
         src = "if (x) { x.foo; // comment\n}"
     parser = Parser(src, filename)
-    x = parser.definition()
-    print(x)
+    while node := parser.definition():
+        pprint.pprint(node)