start a variant of the base64 example with semantic actions

examples/Makefile

@@ -2,7 +2,9 @@
 OUTPUTS := dns.o \
 	   dns \
 	   base64.o \
-	   base64
+	   base64 \
+	   base64_sem1.o \
+	   base64_sem1
 
 TOPLEVEL := ../
 
@@ -12,7 +14,7 @@ LDFLAGS += $(pkg-config --libs glib-2.0)
 
 
 
-all: dns base64
+all: dns base64 base64_sem1
 
 dns: LDFLAGS:=-L../src -lhammer $(LDFLAGS)
 dns: dns.o rr.o dns_common.o
@@ -24,8 +26,8 @@ rr.o: ../src/hammer.h rr.h dns_common.h
 
 dns_common.o: ../src/hammer.h dns_common.h
 
-base64: LDFLAGS:=-L../src -lhammer $(LDFLAGS)
-base64: base64.o
+base64%: LDFLAGS:=-L../src -lhammer $(LDFLAGS)
+base64%: base64%.o
 	$(call hush, "Linking $@") $(CC) -o $@ $^ $(LDFLAGS)
 
-base64.o: ../src/hammer.h
+base64%.o: ../src/hammer.h

examples/base64_sem1.c

@@ -0,0 +1,142 @@
+#include "../src/hammer.h"
+#include <assert.h>
+
+
+#define H_RULE(rule, def) const HParser *rule = def
+#define H_ARULE(rule, def) const HParser *rule = h_action(def, act_ ## rule)
+
+
+///
+// Semantic action helpers.
+// These might be candidates for inclusion in the library.
+///
+
+// The action equivalent of h_ignore.
+const HParsedToken *act_ignore(const HParseResult *p)
+{
+    return NULL;
+}
+
+// Helper to build HAction's that pick one index out of a sequence.
+const HParsedToken *act_index(int i, const HParseResult *p)
+{
+    if(!p) return NULL;
+
+    const HParsedToken *tok = p->ast;
+
+    if(!tok || tok->token_type != TT_SEQUENCE)
+        return NULL;
+
+    const HCountedArray *seq = tok->seq;
+    size_t n = seq->used;
+
+    if(i<0 || (size_t)i>=n)
+        return NULL;
+    else
+        return tok->seq->elements[i];
+}
+
+const HParsedToken *act_index0(const HParseResult *p)
+{
+    return act_index(0, p);
+}
+
+
+///
+// Semantic actions for the grammar below, each corresponds to an "ARULE".
+// They must be named act_<rulename>.
+///
+
+const HParsedToken *act_bsfdig(const HParseResult *p)
+{
+    HParsedToken *res = h_arena_malloc(p->arena, sizeof(HParsedToken));
+
+    assert(p->ast->token_type == TT_UINT);
+    uint8_t c = p->ast->uint;
+
+    res->token_type = TT_UINT;
+    if(c >= 0x40 && c <= 0x5A) // A-Z
+        res->uint = c - 0x41;
+    else if(c >= 0x60 && c <= 0x7A) // a-z
+        res->uint = c - 0x61 + 26;
+    else if(c >= 0x30 && c <= 0x39) // 0-9
+        res->uint = c - 0x30 + 52;
+    else if(c == '+')
+        res->uint = 62;
+    else if(c == '/')
+        res->uint = 63;
+
+    return res;
+}
+
+#define act_bsfdig_4bit  act_bsfdig
+#define act_bsfdig_2bit  act_bsfdig
+
+#define act_equals       act_ignore
+#define act_ws           act_ignore
+
+#define act_document     act_index0
+
+
+///
+// Set up the parser with the grammar to be recognized.
+///
+
+const HParser *init_parser(void)
+{
+    // CORE
+    H_RULE (digit,   h_ch_range(0x30, 0x39));
+    H_RULE (alpha,   h_choice(h_ch_range(0x41, 0x5a), h_ch_range(0x61, 0x7a), NULL));
+    H_RULE (space,   h_in((uint8_t *)" \t\n\r\f\v", 6));
+
+    // AUX.
+    H_RULE (plus,    h_ch('+'));
+    H_RULE (slash,   h_ch('/'));
+    H_ARULE(equals,  h_ch('='));
+
+    H_ARULE(bsfdig,       h_choice(alpha, digit, plus, slash, NULL));
+    H_ARULE(bsfdig_4bit,  h_in((uint8_t *)"AEIMQUYcgkosw048", 16));
+    H_ARULE(bsfdig_2bit,  h_in((uint8_t *)"AQgw", 4));
+    H_RULE (base64_3,     h_repeat_n(bsfdig, 4));
+    H_RULE (base64_2,     h_sequence(bsfdig, bsfdig, bsfdig_4bit, equals, NULL));
+    H_RULE (base64_1,     h_sequence(bsfdig, bsfdig_2bit, equals, equals, NULL));
+    H_RULE (base64,       h_sequence(h_many(base64_3),
+                                     h_optional(h_choice(base64_2,
+                                                         base64_1, NULL)),
+                                     NULL));
+
+    H_ARULE(ws,           h_many(space));
+    H_ARULE(document,     h_sequence(ws, base64, ws, h_end_p(), NULL));
+
+    return document;
+}
+
+
+///
+// Main routine: print input, parse, print result, return success/failure.
+///
+
+#include <stdio.h>
+
+int main(int argc, char **argv)
+{
+    uint8_t input[102400];
+    size_t inputsize;
+    const HParser *parser;
+    const HParseResult *result;
+
+    parser = init_parser();
+
+    inputsize = fread(input, 1, sizeof(input), stdin);
+    fprintf(stderr, "inputsize=%lu\ninput=", inputsize);
+    fwrite(input, 1, inputsize, stderr);
+    result = h_parse(parser, input, inputsize);
+
+    if(result) {
+        fprintf(stderr, "parsed=%lld bytes\n", result->bit_length/8);
+        h_pprint(stdout, result->ast, 0, 0);
+        return 0;
+    } else {
+        return 1;
+    }
+}