From c7cb1dfcb9f89eb0a2d2a90a5e496e919c8a0b94 Mon Sep 17 00:00:00 2001
From: Damien George <damien.p.george@gmail.com>
Date: Fri, 29 Dec 2017 00:53:57 +1100
Subject: [PATCH] py/parse: Fix macro evaluation by avoiding empty __VA_ARGS__.
Empty __VA_ARGS__ are not allowed in the C preprocessor so adjust the rule
arg offset calculation to not use them. Also, some compilers (eg MSVC)
require an extra layer of macro expansion.
---
py/parse.c | 27 +++++++++++++++++----------
1 file changed, 17 insertions(+), 10 deletions(-)
diff --git a/py/parse.c b/py/parse.c
index 238c94695..8c1286492 100644
--- a/py/parse.c
+++ b/py/parse.c
@@ -131,39 +131,46 @@ STATIC const uint16_t rule_arg_combined_table[] = {
#undef opt_rule
};
-// Macro to create a list of N-1 identifiers where N is the number of variable arguments to the macro
+// Macro to create a list of N identifiers where N is the number of variable arguments to the macro
+#define RULE_EXPAND(x) x
#define RULE_PADDING(rule, ...) RULE_PADDING2(rule, __VA_ARGS__, RULE_PADDING_IDS(rule))
-#define RULE_PADDING2(rule, ...) RULE_PADDING3(rule, __VA_ARGS__)
-#define RULE_PADDING3(rule, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, ...) __VA_ARGS__
+#define RULE_PADDING2(rule, ...) RULE_EXPAND(RULE_PADDING3(rule, __VA_ARGS__))
+#define RULE_PADDING3(rule, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, ...) __VA_ARGS__
#define RULE_PADDING_IDS(r) PAD12_##r, PAD11_##r, PAD10_##r, PAD9_##r, PAD8_##r, PAD7_##r, PAD6_##r, PAD5_##r, PAD4_##r, PAD3_##r, PAD2_##r, PAD1_##r,
-// Use an enum to create constants that specify where in rule_arg_combined_table a given rule starts
+// Use an enum to create constants specifying how much room a rule takes in rule_arg_combined_table
enum {
-#define DEF_RULE(rule, comp, kind, ...) RULE_ARG_OFFSET_##rule, RULE_PADDING(rule, __VA_ARGS__)
+#define DEF_RULE(rule, comp, kind, ...) RULE_PADDING(rule, __VA_ARGS__)
#define DEF_RULE_NC(rule, kind, ...)
#include "py/grammar.h"
#undef DEF_RULE
#undef DEF_RULE_NC
#define DEF_RULE(rule, comp, kind, ...)
-#define DEF_RULE_NC(rule, kind, ...) RULE_ARG_OFFSET_##rule, RULE_PADDING(rule, __VA_ARGS__)
+#define DEF_RULE_NC(rule, kind, ...) RULE_PADDING(rule, __VA_ARGS__)
#include "py/grammar.h"
#undef DEF_RULE
#undef DEF_RULE_NC
};
+// Macro to compute the start of a rule in rule_arg_combined_table
+#define RULE_ARG_OFFSET(rule, ...) RULE_ARG_OFFSET2(rule, __VA_ARGS__, RULE_ARG_OFFSET_IDS(rule))
+#define RULE_ARG_OFFSET2(rule, ...) RULE_EXPAND(RULE_ARG_OFFSET3(rule, __VA_ARGS__))
+#define RULE_ARG_OFFSET3(rule, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, ...) _13
+#define RULE_ARG_OFFSET_IDS(r) PAD12_##r, PAD11_##r, PAD10_##r, PAD9_##r, PAD8_##r, PAD7_##r, PAD6_##r, PAD5_##r, PAD4_##r, PAD3_##r, PAD2_##r, PAD1_##r, PAD0_##r,
+
// Use the above enum values to create a table of offsets for each rule's arg
// data, which indexes rule_arg_combined_table. The offsets require 9 bits of
// storage but only the lower 8 bits are stored here. The 9th bit is computed
// in get_rule_arg using the FIRST_RULE_WITH_OFFSET_ABOVE_255 constant.
STATIC const uint8_t rule_arg_offset_table[] = {
-#define DEF_RULE(rule, comp, kind, ...) RULE_ARG_OFFSET_##rule & 0xff,
+#define DEF_RULE(rule, comp, kind, ...) RULE_ARG_OFFSET(rule, __VA_ARGS__) & 0xff,
#define DEF_RULE_NC(rule, kind, ...)
#include "py/grammar.h"
#undef DEF_RULE
#undef DEF_RULE_NC
0, // RULE_const_object
#define DEF_RULE(rule, comp, kind, ...)
-#define DEF_RULE_NC(rule, kind, ...) RULE_ARG_OFFSET_##rule & 0xff,
+#define DEF_RULE_NC(rule, kind, ...) RULE_ARG_OFFSET(rule, __VA_ARGS__) & 0xff,
#include "py/grammar.h"
#undef DEF_RULE
#undef DEF_RULE_NC
@@ -171,13 +178,13 @@ STATIC const uint8_t rule_arg_offset_table[] = {
// Define a constant that's used to determine the 9th bit of the values in rule_arg_offset_table
static const size_t FIRST_RULE_WITH_OFFSET_ABOVE_255 =
-#define DEF_RULE(rule, comp, kind, ...) RULE_ARG_OFFSET_##rule >= 0x100 ? RULE_##rule :
+#define DEF_RULE(rule, comp, kind, ...) RULE_ARG_OFFSET(rule, __VA_ARGS__) >= 0x100 ? RULE_##rule :
#define DEF_RULE_NC(rule, kind, ...)
#include "py/grammar.h"
#undef DEF_RULE
#undef DEF_RULE_NC
#define DEF_RULE(rule, comp, kind, ...)
-#define DEF_RULE_NC(rule, kind, ...) RULE_ARG_OFFSET_##rule >= 0x100 ? RULE_##rule :
+#define DEF_RULE_NC(rule, kind, ...) RULE_ARG_OFFSET(rule, __VA_ARGS__) >= 0x100 ? RULE_##rule :
#include "py/grammar.h"
#undef DEF_RULE
#undef DEF_RULE_NC
--
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