Simplify string formatter API.

Emit characters with callbacks so we don't need to do two passes using
vsnprintf to count, format, and copy the result.

3 files changed, 74 insertions, 78 deletions

diff --git a/source/fitz/buffer.c b/source/fitz/buffer.c
index ab814728..d432e810 100644
--- a/source/fitz/buffer.c
+++ b/source/fitz/buffer.c
@@ -331,45 +331,24 @@ fz_append_bits_pad(fz_context *ctx, fz_buffer *buf)
 	buf->unused_bits = 0;
 }
 
-size_t
+static void fz_append_emit(fz_context *ctx, void *buffer, int c)
+{
+	fz_append_byte(ctx, buffer, c);
+}
+
+void
 fz_append_printf(fz_context *ctx, fz_buffer *buffer, const char *fmt, ...)
 {
-	size_t ret;
 	va_list args;
 	va_start(args, fmt);
-	ret = fz_append_vprintf(ctx, buffer, fmt, args);
+	fz_format_string(ctx, buffer, fz_append_emit, fmt, args);
 	va_end(args);
-	return ret;
 }
 
-size_t
-fz_append_vprintf(fz_context *ctx, fz_buffer *buffer, const char *fmt, va_list old_args)
+void
+fz_append_vprintf(fz_context *ctx, fz_buffer *buffer, const char *fmt, va_list args)
 {
-	size_t slack;
-	size_t len;
-	va_list args;
-
-	slack = buffer->cap - buffer->len;
-	va_copy(args, old_args);
-	len = fz_vsnprintf((char *)buffer->data + buffer->len, slack, fmt, args);
-	va_copy_end(args);
-
-	/* len is the number of characters in the formatted string (not including
-	 * the terminating zero), so if (len > slack) the string was truncated. */
-	if (len > slack)
-	{
-		/* Grow the buffer and retry */
-		fz_ensure_buffer(ctx, buffer, buffer->len + len);
-		slack = buffer->cap - buffer->len;
-
-		va_copy(args, old_args);
-		len = fz_vsnprintf((char *)buffer->data + buffer->len, slack, fmt, args);
-		va_copy_end(args);
-	}
-
-	buffer->len += len;
-
-	return len;
+	fz_format_string(ctx, buffer, fz_append_emit, fmt, args);
 }
 
 void
diff --git a/source/fitz/output.c b/source/fitz/output.c
index bd4dba66..961bafe5 100644
--- a/source/fitz/output.c
+++ b/source/fitz/output.c
@@ -266,36 +266,17 @@ fz_tell_output(fz_context *ctx, fz_output *out)
 	return out->tell(ctx, out->state);
 }
 
-void
-fz_write_vprintf(fz_context *ctx, fz_output *out, const char *fmt, va_list old_args)
+static void
+fz_write_emit(fz_context *ctx, void *out, int c)
 {
-	char buffer[256], *p = buffer;
-	size_t len;
-	va_list args;
+	fz_write_byte(ctx, out, c);
+}
 
+void
+fz_write_vprintf(fz_context *ctx, fz_output *out, const char *fmt, va_list args)
+{
 	if (!out) return;
-
-	/* First try using our fixed size buffer */
-	va_copy(args, old_args);
-	len = fz_vsnprintf(buffer, sizeof buffer, fmt, args);
-	va_copy_end(args);
-
-	/* If that failed, allocate a big enough buffer */
-	if (len > sizeof buffer)
-	{
-		p = fz_malloc(ctx, len);
-		va_copy(args, old_args);
-		fz_vsnprintf(p, len, fmt, args);
-		va_copy_end(args);
-	}
-
-	fz_try(ctx)
-		out->write(ctx, out->state, p, len);
-	fz_always(ctx)
-		if (p != buffer)
-			fz_free(ctx, p);
-	fz_catch(ctx)
-		fz_rethrow(ctx);
+	fz_format_string(ctx, out, fz_write_emit, fmt, args);
 }
 
 void
@@ -304,7 +285,7 @@ fz_write_printf(fz_context *ctx, fz_output *out, const char *fmt, ...)
 	va_list args;
 	if (!out) return;
 	va_start(args, fmt);
-	fz_write_vprintf(ctx, out, fmt, args);
+	fz_format_string(ctx, out, fz_write_emit, fmt, args);
 	va_end(args);
 }
 
diff --git a/source/fitz/printf.c b/source/fitz/printf.c
index 65c98278..d0f95327 100644
--- a/source/fitz/printf.c
+++ b/source/fitz/printf.c
@@ -4,16 +4,14 @@ static const char *fz_hex_digits = "0123456789abcdef";
 
 struct fmtbuf
 {
-	char *p;
-	size_t s;
-	size_t n;
+	fz_context *ctx;
+	void *user;
+	void (*emit)(fz_context *ctx, void *user, int c);
 };
 
-static void fmtputc(struct fmtbuf *out, int c)
+static inline void fmtputc(struct fmtbuf *out, int c)
 {
-	if (out->n < out->s)
-		out->p[out->n] = c;
-	++(out->n);
+	out->emit(out->ctx, out->user, c);
 }
 
 /*
@@ -151,29 +149,31 @@ static void fmtquote(struct fmtbuf *out, const char *s, int sq, int eq)
 	fmtputc(out, eq);
 }
 
-size_t
-fz_vsnprintf(char *buffer, size_t space, const char *fmt, va_list args)
+void
+fz_format_string(fz_context *ctx, void *user, void (*emit)(fz_context *ctx, void *user, int c), const char *fmt, va_list args)
 {
 	struct fmtbuf out;
+	int c, i, n, z;
 	fz_matrix *m;
 	fz_rect *r;
 	fz_point *p;
-	int c, i, n, z;
 	int64_t i64;
 	double f;
 	char *s;
 	size_t length;
 
-	out.p = buffer;
-	out.s = space;
-	out.n = 0;
+	out.ctx = ctx;
+	out.user = user;
+	out.emit = emit;
 
 	while ((c = *fmt++) != 0)
 	{
-		if (c == '%') {
+		if (c == '%')
+		{
 			c = *fmt++;
 			if (c == 0)
 				break;
+
 			z = 1;
 			if (c == '0' && fmt[0] && fmt[1]) {
 				z = *fmt++ - '0';
@@ -184,6 +184,7 @@ fz_vsnprintf(char *buffer, size_t space, const char *fmt, va_list args)
 					c = *fmt++;
 				}
 			}
+
 			/* Check for lengths */
 			length = 0;
 			switch (c) {
@@ -213,6 +214,7 @@ fz_vsnprintf(char *buffer, size_t space, const char *fmt, va_list args)
 				if (c == 0)
 					break; /* Can't warn :( */
 			}
+
 			switch (c) {
 			default:
 				fmtputc(&out, '%');
@@ -326,22 +328,56 @@ fz_vsnprintf(char *buffer, size_t space, const char *fmt, va_list args)
 				fmtquote(&out, s, '(', ')');
 				break;
 			}
-		} else {
+		}
+		else
+		{
 			fmtputc(&out, c);
 		}
 	}
+}
 
-	fmtputc(&out, 0);
+struct snprintf_buffer
+{
+	char *p;
+	size_t s, n;
+};
+
+static void snprintf_emit(fz_context *ctx, void *out_, int c)
+{
+	struct snprintf_buffer *out = out_;
+	if (out->n < out->s)
+		out->p[out->n] = c;
+	++(out->n);
+}
+
+size_t
+fz_vsnprintf(char *buffer, size_t space, const char *fmt, va_list args)
+{
+	struct snprintf_buffer out;
+	out.p = buffer;
+	out.s = space;
+	out.n = 0;
+
+	/* Note: using a NULL context is safe here */
+	fz_format_string(NULL, &out, snprintf_emit, fmt, args);
+	snprintf_emit(NULL, &out, 0);
 	return out.n - 1;
 }
 
 size_t
 fz_snprintf(char *buffer, size_t space, const char *fmt, ...)
 {
-	size_t n;
 	va_list ap;
+	struct snprintf_buffer out;
+	out.p = buffer;
+	out.s = space;
+	out.n = 0;
+
 	va_start(ap, fmt);
-	n = fz_vsnprintf(buffer, space, fmt, ap);
+	/* Note: using a NULL context is safe here */
+	fz_format_string(NULL, &out, snprintf_emit, fmt, ap);
+	snprintf_emit(NULL, &out, 0);
 	va_end(ap);
-	return n;
+
+	return out.n - 1;
 }