display: Added format string generator function based on display flags.

TODO: Format string generator function uses a lot of ugly and unsafe hacks, rewrite it to do better bounds checking and more safe and efficient string concatenation.

Fortune for naka's current commit: Future blessing − 末吉

include/display.h

@@ -16,15 +16,20 @@ typedef enum display_kind {
 
 #define X(n) AS(1lu << (n), usize)
 typedef enum display_flags {
+	// Show the number (index) of they haystack matched
 	DISPF_SHOW_NUMBER =	X(0),
-	DISPF_SHOW_LENGTH =	X(1),
-	DISPF_SHOW_SLICE  =	X(2),
+	// Show the slice
+	DISPF_SHOW_SLICE  =	X(1),
+	// Show the length of the slice
+	DISPF_SHOW_LENGTH =	X(2),
+	// Show failed matches
 	DISPF_SHOW_FAILURES =	X(3),
 } dispflags_t;
 #define DISPLAY_FLAGS_DEFAULT (DISPF_SHOW_SLICE | DISPF_SHOW_NUMBER | DISPF_SHOW_FAILURES)
 #undef X
 
-typedef struct {
+typedef struct {	
+	bool matched;
 	slice_t cslice;
 	const void* base;
 	usize index;

src/display.c

@@ -2,13 +2,36 @@
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 
 #include <macros.h>
 #include <comp.h>
 #include <display.h>
 
+#define FLAGSET(f, flag) (( (f) & (flag) ) == (flag))
+#define DFLAGSET(f, flagname) FLAGSET(f, DISPF_SHOW_ ## flagname)
+
+//TODO: This probably won't work. Write wrappers for strncpy(), strncat() that return number of bytes written isntead of useless pointer that we already have.
+static usize _display_get_fmt(dispflags_t flags, bool matched, usize _len, char str[pOUT _len])
+{
+	register usize len = _len;
+	static const char* fmts[] = { "match: ", "%lu: ", SLICE_FORMAT, " (len %lu)", "failure: ", (const char*)NULL };
+#define ADDSTR(s) do { debug_assert((s)); strncat(str, (s), len); w = strlen((s)); w = w > len ? len : w; ifU(len<=w) { str[len-1] = 0; return w; } len -= w; str += w; fw+=w; } while(0)
+	usize fw;
+	usize w = strlen(strncpy(str, matched ? fmts[0] 
+					: DFLAGSET(flags, FAILURES) ? fmts[4]
+					: "", len)); if(len<=w || w == 0) { str[len-1] = 0; return 0; } len -= w; str += w; fw = w;
+	if(DFLAGSET(flags, NUMBER)) ADDSTR(fmts[1]);
+	if(DFLAGSET(flags, SLICE)) ADDSTR(fmts[2]);
+	if(DFLAGSET(flags, LENGTH)) ADDSTR(fmts[3]);
+	ADDSTR("\n");
+	TRACE("Output string written: %lu, (rlen %lu)", fw, len);
+	return fw;
+}
+
 static void _display_normal(FILE* output, dispin_t*pIN input, dispflags_t flags)
 {
+	bool matched = input->matched;
 	slice_t cslice = input->cslice;
 	const void* base = input->base;
 	usize i = input->index;
@@ -25,16 +48,16 @@ static void _display_normal(FILE* output, dispin_t*pIN input, dispflags_t flags)
 #endif
 	INFO("Mapped region slice for %lu, pre-transform (at %p): " SLICE_FORMAT ", len: %lu", i+1, base, SLICE_FORMAT_ARGS(&cslice), cslice.len);
 
-	//TODO: Honour `flags`
-	IGNORE(flags);
-	fprintf(output, "match: %lu: %lu -> %lu\n", i+1, pos.start, pos.end);
+	//Honour `flags`
+	char fmt[200]; //TODO: Find the realistic max for this.
+	fmt[_display_get_fmt(flags, matched, 100, fmt)] = 0;
+	fprintf(output, fmt, i+1, pos.start, pos.end, pos.end-pos.start);
 } 
 
 void display_result(FILE* output, dispin_t input, dispkind_t how, dispflags_t flags)
 {
 	flags = flags ?: DISPLAY_FLAGS_DEFAULT;
 	output = output ?: stdout;
-	debug_assert(input);
 
 	TRACE("Outputting as %d to %p with flags 0x%08lx", (int)how, output, (usize)flags);
 	switch(how)

src/main.c

@@ -178,11 +178,12 @@ inv_args:
 	{
 		slice_t cslice;
 		const void* base = current->mapping->origin;
+		bool matched = current->matched;
 		if(!comp_slice_of(&needle, current++, &cslice)) {
 			printf("fail: %lu\n", i+1);
 		} else {
 			TRACE("Displaying result %lu (" SLICE_FORMAT ") (base %p)", i, SLICE_FORMAT_ARGS(&cslice), base);
-			display_result(stdout, (dispin_t){ .base = base, .cslice = cslice, .index = i}, DISPK_NORMAL, 0); 
+			display_result(stdout, (dispin_t){ .base = base, .cslice = cslice, .index = i, .matched = matched }, DISPK_NORMAL, 0); 
 		}
 	}