Add jxpretty example

dist-files/Makefile.jxpretty

@@ -0,0 +1,8 @@
+#
+#  Example Makefile for building the jxpretty example
+#
+
+jxpretty:
+	gcc -o $@ -std=c99 -Wall -Wextra -O2 -Isrc \
+		src/duktape.c examples/jxpretty/jxpretty.c \
+		-lm

examples/jxpretty/README.rst

@@ -0,0 +1,5 @@
+================
+Jxpretty example
+================
+
+Simple command line utility to pretty print JSON in the JX format.

examples/jxpretty/jxpretty.c

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+/*
+ *  Pretty print JSON from stdin into indented JX.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include "duktape.h"
+
+static duk_ret_t do_jxpretty(duk_context *ctx) {
+	FILE *f = stdin;
+	char buf[4096];
+	size_t ret;
+
+	for (;;) {
+		if (ferror(f)) {
+			duk_error(ctx, DUK_ERR_ERROR, "ferror() on stdin");
+		}
+		if (feof(f)) {
+			break;
+		}
+
+		ret = fread(buf, 1, sizeof(buf), f);
+#if 0
+		fprintf(stderr, "Read: %ld\n", (long) ret);
+		fflush(stderr);
+#endif
+		if (ret == 0) {
+			break;
+		}
+
+		duk_require_stack(ctx, 1);
+		duk_push_lstring(ctx, (const char *) buf, ret);
+	}
+
+	duk_concat(ctx, duk_get_top(ctx));
+
+	duk_eval_string(ctx, "(function (v) { print(Duktape.enc('jx', JSON.parse(v), null, 4)); })");
+	duk_insert(ctx, -2);
+	duk_call(ctx, 1);
+
+	return 0;
+}
+
+int main(int argc, char *argv[]) {
+	duk_context *ctx;
+	duk_int_t rc;
+
+	/* suppress warnings */
+	(void) argc;
+	(void) argv;
+
+	ctx = duk_create_heap_default();
+
+	rc = duk_safe_call(ctx, do_jxpretty, 0 /*nargs*/, 1 /*nrets*/);
+	if (rc) {
+		fprintf(stderr, "ERROR: %s\n", duk_safe_to_string(ctx, -1));
+		fflush(stderr);
+	}
+
+	duk_destroy_heap(ctx);
+
+	return 0;
+}