From c5d9bae0b7c37443112ea13b74d7298e9c8413af Mon Sep 17 00:00:00 2001
From: Andrea Shepard <andrea@persephoneslair.org>
Date: Sun, 7 May 2017 17:56:20 +0000
Subject: [PATCH] Add PB_INVALID, the missing backend, h_get_default_backend()
and h_is_backend_available()
---
src/SConscript | 5 +++--
src/backends/missing.c | 25 +++++++++++++++++++++++++
src/backends/missing.h | 7 +++++++
src/hammer.c | 27 +++++++++++++++++++++------
src/hammer.h | 18 +++++++++++++++++-
src/internal.h | 14 ++++++++++++++
6 files changed, 87 insertions(+), 9 deletions(-)
create mode 100644 src/backends/missing.c
create mode 100644 src/backends/missing.h
diff --git a/src/SConscript b/src/SConscript
index 0c4f81ed..2af08ae1 100644
--- a/src/SConscript
+++ b/src/SConscript
@@ -21,7 +21,8 @@ parsers_headers = [
backends_headers = [
'backends/regex.h',
- 'backends/contextfree.h'
+ 'backends/contextfree.h',
+ 'backends/missing.h'
]
parsers = ['parsers/%s.c'%s for s in
@@ -55,7 +56,7 @@ parsers = ['parsers/%s.c'%s for s in
'value']]
backends = ['backends/%s.c' % s for s in
- ['packrat', 'llk', 'regex', 'glr', 'lalr', 'lr', 'lr0']]
+ ['missing', 'packrat', 'llk', 'regex', 'glr', 'lalr', 'lr', 'lr0']]
misc_hammer_parts = [
'allocator.c',
diff --git a/src/backends/missing.c b/src/backends/missing.c
new file mode 100644
index 00000000..f159bf19
--- /dev/null
+++ b/src/backends/missing.c
@@ -0,0 +1,25 @@
+#include "missing.h"
+
+/* Placeholder backend that always fails */
+
+int h_missing_compile(HAllocator* mm__, HParser* parser, const void* params) {
+ /* Always fail */
+
+ return -1;
+}
+
+HParseResult *h_missing_parse(HAllocator* mm__, const HParser* parser, HInputStream* stream) {
+ /* Always fail */
+
+ return NULL;
+}
+
+void h_missing_free(HParser *parser) {
+ /* No-op */
+}
+
+HParserBackendVTable h__missing_backend_vtable = {
+ .compile = h_missing_compile,
+ .parse = h_missing_parse,
+ .free = h_missing_free,
+};
diff --git a/src/backends/missing.h b/src/backends/missing.h
new file mode 100644
index 00000000..4efe5f35
--- /dev/null
+++ b/src/backends/missing.h
@@ -0,0 +1,7 @@
+#ifndef HAMMER_BACKENDS_MISSING__H
+#define HAMMER_BACKENDS_MISSING__H
+
+#include "../hammer.h"
+#include "../internal.h"
+
+#endif /* !defined(HAMMER_BACKENDS_MISSING__H) */
diff --git a/src/hammer.c b/src/hammer.c
index 70ebc8a4..44ff2e66 100644
--- a/src/hammer.c
+++ b/src/hammer.c
@@ -26,11 +26,12 @@
#include "parsers/parser_internal.h"
static HParserBackendVTable *backends[PB_MAX + 1] = {
- &h__packrat_backend_vtable,
- &h__regex_backend_vtable,
- &h__llk_backend_vtable,
- &h__lalr_backend_vtable,
- &h__glr_backend_vtable,
+ &h__missing_backend_vtable, /* For PB_INVALID */
+ &h__packrat_backend_vtable, /* For PB_PACKRAT */
+ &h__regex_backend_vtable, /* For PB_REGULAR */
+ &h__llk_backend_vtable, /* For PB_LLk */
+ &h__lalr_backend_vtable, /* For PB_LALR */
+ &h__glr_backend_vtable /* For PB_GLR */
};
@@ -41,7 +42,18 @@ typedef struct {
const HParser *p2;
} HTwoParsers;
+/* Backend-related inquiries */
+int h_is_backend_available(HParserBackend backend) {
+ if (backend >= PB_MIN && backend <= PB_MAX) {
+ return (backends[backend] != &h__missing_backend_vtable) ? 1 : 0;
+ } else return 0;
+}
+
+HParserBackend h_get_default_backend(void) {
+ /* Call the inline version in internal.h */
+ return h_get_default_backend__int();
+}
#define DEFAULT_ENDIANNESS (BIT_BIG_ENDIAN | BYTE_BIG_ENDIAN)
@@ -93,7 +105,10 @@ int h_compile(HParser* parser, HParserBackend backend, const void* params) {
}
int h_compile__m(HAllocator* mm__, HParser* parser, HParserBackend backend, const void* params) {
- backends[parser->backend]->free(parser);
+ if (parser->backend >= PB_MIN && parser->backend <= PB_MAX &&
+ backends[parser->backend]->free != NULL) {
+ backends[parser->backend]->free(parser);
+ }
int ret = backends[backend]->compile(mm__, parser, params);
if (!ret)
parser->backend = backend;
diff --git a/src/hammer.h b/src/hammer.h
index ad44fee9..a9ace572 100644
--- a/src/hammer.h
+++ b/src/hammer.h
@@ -41,7 +41,12 @@ typedef struct HParseState_ HParseState;
typedef enum HParserBackend_ {
PB_MIN = 0,
- PB_PACKRAT = PB_MIN, // PB_MIN is always the default.
+ /*
+ * Have a backend that always fails to pass around "no such backend"
+ * indications
+ */
+ PB_INVALID = PB_MIN,
+ PB_PACKRAT,
PB_REGULAR,
PB_LLk,
PB_LALR,
@@ -260,6 +265,17 @@ typedef struct HBenchmarkResults_ {
#endif // SWIG
// }}}
+/**
+ * Ask if this backend is available
+ */
+
+int h_is_backend_available(HParserBackend backend);
+
+/**
+ * Ask what the default backend is (currently always PB_PACKRAT)
+ */
+
+HParserBackend h_get_default_backend(void);
/**
* Top-level function to call a parser that has been built over some
diff --git a/src/internal.h b/src/internal.h
index 0e92e99e..51898bf0 100644
--- a/src/internal.h
+++ b/src/internal.h
@@ -318,6 +318,7 @@ struct HBitWriter_ {
// Backends {{{
+extern HParserBackendVTable h__missing_backend_vtable;
extern HParserBackendVTable h__packrat_backend_vtable;
extern HParserBackendVTable h__llk_backend_vtable;
extern HParserBackendVTable h__lalr_backend_vtable;
@@ -334,12 +335,25 @@ static inline size_t h_input_stream_pos(HInputStream* state) {
HParseResult* h_do_parse(const HParser* parser, HParseState *state);
void put_cached(HParseState *ps, const HParser *p, HParseResult *cached);
+/*
+ * Inline this for benefit of h_new_parser() below, then make
+ * the API h_get_default_backend() call it.
+ */
+static inline HParserBackend h_get_default_backend__int(void) {
+ return PB_PACKRAT;
+}
+
static inline
HParser *h_new_parser(HAllocator *mm__, const HParserVtable *vt, void *env) {
HParser *p = h_new(HParser, 1);
memset(p, 0, sizeof(HParser));
p->vtable = vt;
p->env = env;
+ /*
+ * Current limitation: if we specify backends solely by HParserBackend, we
+ * can't set a default backend that requires any parameters to h_compile()
+ */
+ p->backend = h_get_default_backend__int();
return p;
}
--
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