summaryrefslogtreecommitdiff
path: root/json-writer.c
diff options
context:
space:
mode:
authorJeff Hostetler <jeffhost@microsoft.com>2018-07-13 16:54:08 +0000
committerJunio C Hamano <gitster@pobox.com>2018-07-16 13:55:39 -0700
commit75459410edd8d3bf38a2f1ad785f54b97770b324 (patch)
tree2b5d0ed8135d0e2649ebf26f577f26030fb185af /json-writer.c
parentb2453d34496cb62b9c63c7a7c9b4bead2431f715 (diff)
downloadgit-75459410edd8d3bf38a2f1ad785f54b97770b324.tar.gz
json_writer: new routines to create JSON data
Add "struct json_writer" and a series of jw_ routines to compose JSON data into a string buffer. The resulting string may then be printed by commands wanting to support a JSON-like output format. The json_writer is limited to correctly formatting structured data for output. It does not attempt to build an object model of the JSON data. We say "JSON-like" because we do not enforce the Unicode (usually UTF-8) requirement on string fields. Internally, Git does not necessarily have Unicode/UTF-8 data for most fields, so it is currently unclear the best way to enforce that requirement. For example, on Linux pathnames can contain arbitrary 8-bit character data, so a command like "status" would not know how to encode the reported pathnames. We may want to revisit this (or double encode such strings) in the future. Helped-by: Eric Sunshine <sunshine@sunshineco.com> Helped-by: René Scharfe <l.s.r@web.de> Helped-by: Wink Saville <wink@saville.com> Helped-by: Ramsay Jones <ramsay@ramsayjones.plus.com> Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'json-writer.c')
-rw-r--r--json-writer.c414
1 files changed, 414 insertions, 0 deletions
diff --git a/json-writer.c b/json-writer.c
new file mode 100644
index 0000000000..aadb9dbddc
--- /dev/null
+++ b/json-writer.c
@@ -0,0 +1,414 @@
+#include "cache.h"
+#include "json-writer.h"
+
+void jw_init(struct json_writer *jw)
+{
+ strbuf_init(&jw->json, 0);
+ strbuf_init(&jw->open_stack, 0);
+ jw->need_comma = 0;
+ jw->pretty = 0;
+}
+
+void jw_release(struct json_writer *jw)
+{
+ strbuf_release(&jw->json);
+ strbuf_release(&jw->open_stack);
+}
+
+/*
+ * Append JSON-quoted version of the given string to 'out'.
+ */
+static void append_quoted_string(struct strbuf *out, const char *in)
+{
+ unsigned char c;
+
+ strbuf_addch(out, '"');
+ while ((c = *in++) != '\0') {
+ if (c == '"')
+ strbuf_addstr(out, "\\\"");
+ else if (c == '\\')
+ strbuf_addstr(out, "\\\\");
+ else if (c == '\n')
+ strbuf_addstr(out, "\\n");
+ else if (c == '\r')
+ strbuf_addstr(out, "\\r");
+ else if (c == '\t')
+ strbuf_addstr(out, "\\t");
+ else if (c == '\f')
+ strbuf_addstr(out, "\\f");
+ else if (c == '\b')
+ strbuf_addstr(out, "\\b");
+ else if (c < 0x20)
+ strbuf_addf(out, "\\u%04x", c);
+ else
+ strbuf_addch(out, c);
+ }
+ strbuf_addch(out, '"');
+}
+
+static void indent_pretty(struct json_writer *jw)
+{
+ int k;
+
+ for (k = 0; k < jw->open_stack.len; k++)
+ strbuf_addstr(&jw->json, " ");
+}
+
+/*
+ * Begin an object or array (either top-level or nested within the currently
+ * open object or array).
+ */
+static void begin(struct json_writer *jw, char ch_open, int pretty)
+{
+ jw->pretty = pretty;
+
+ strbuf_addch(&jw->json, ch_open);
+
+ strbuf_addch(&jw->open_stack, ch_open);
+ jw->need_comma = 0;
+}
+
+/*
+ * Assert that the top of the open-stack is an object.
+ */
+static void assert_in_object(const struct json_writer *jw, const char *key)
+{
+ if (!jw->open_stack.len)
+ BUG("json-writer: object: missing jw_object_begin(): '%s'", key);
+ if (jw->open_stack.buf[jw->open_stack.len - 1] != '{')
+ BUG("json-writer: object: not in object: '%s'", key);
+}
+
+/*
+ * Assert that the top of the open-stack is an array.
+ */
+static void assert_in_array(const struct json_writer *jw)
+{
+ if (!jw->open_stack.len)
+ BUG("json-writer: array: missing jw_array_begin()");
+ if (jw->open_stack.buf[jw->open_stack.len - 1] != '[')
+ BUG("json-writer: array: not in array");
+}
+
+/*
+ * Add comma if we have already seen a member at this level.
+ */
+static void maybe_add_comma(struct json_writer *jw)
+{
+ if (jw->need_comma)
+ strbuf_addch(&jw->json, ',');
+ else
+ jw->need_comma = 1;
+}
+
+static void fmt_double(struct json_writer *jw, int precision,
+ double value)
+{
+ if (precision < 0) {
+ strbuf_addf(&jw->json, "%f", value);
+ } else {
+ struct strbuf fmt = STRBUF_INIT;
+ strbuf_addf(&fmt, "%%.%df", precision);
+ strbuf_addf(&jw->json, fmt.buf, value);
+ strbuf_release(&fmt);
+ }
+}
+
+static void object_common(struct json_writer *jw, const char *key)
+{
+ assert_in_object(jw, key);
+ maybe_add_comma(jw);
+
+ if (jw->pretty) {
+ strbuf_addch(&jw->json, '\n');
+ indent_pretty(jw);
+ }
+
+ append_quoted_string(&jw->json, key);
+ strbuf_addch(&jw->json, ':');
+ if (jw->pretty)
+ strbuf_addch(&jw->json, ' ');
+}
+
+static void array_common(struct json_writer *jw)
+{
+ assert_in_array(jw);
+ maybe_add_comma(jw);
+
+ if (jw->pretty) {
+ strbuf_addch(&jw->json, '\n');
+ indent_pretty(jw);
+ }
+}
+
+/*
+ * Assert that the given JSON object or JSON array has been properly
+ * terminated. (Has closing bracket.)
+ */
+static void assert_is_terminated(const struct json_writer *jw)
+{
+ if (jw->open_stack.len)
+ BUG("json-writer: object: missing jw_end(): '%s'",
+ jw->json.buf);
+}
+
+void jw_object_begin(struct json_writer *jw, int pretty)
+{
+ begin(jw, '{', pretty);
+}
+
+void jw_object_string(struct json_writer *jw, const char *key, const char *value)
+{
+ object_common(jw, key);
+ append_quoted_string(&jw->json, value);
+}
+
+void jw_object_intmax(struct json_writer *jw, const char *key, intmax_t value)
+{
+ object_common(jw, key);
+ strbuf_addf(&jw->json, "%"PRIdMAX, value);
+}
+
+void jw_object_double(struct json_writer *jw, const char *key, int precision,
+ double value)
+{
+ object_common(jw, key);
+ fmt_double(jw, precision, value);
+}
+
+void jw_object_true(struct json_writer *jw, const char *key)
+{
+ object_common(jw, key);
+ strbuf_addstr(&jw->json, "true");
+}
+
+void jw_object_false(struct json_writer *jw, const char *key)
+{
+ object_common(jw, key);
+ strbuf_addstr(&jw->json, "false");
+}
+
+void jw_object_bool(struct json_writer *jw, const char *key, int value)
+{
+ if (value)
+ jw_object_true(jw, key);
+ else
+ jw_object_false(jw, key);
+}
+
+void jw_object_null(struct json_writer *jw, const char *key)
+{
+ object_common(jw, key);
+ strbuf_addstr(&jw->json, "null");
+}
+
+static void increase_indent(struct strbuf *sb,
+ const struct json_writer *jw,
+ int indent)
+{
+ int k;
+
+ strbuf_reset(sb);
+ for (k = 0; k < jw->json.len; k++) {
+ char ch = jw->json.buf[k];
+ strbuf_addch(sb, ch);
+ if (ch == '\n')
+ strbuf_addchars(sb, ' ', indent);
+ }
+}
+
+static void kill_indent(struct strbuf *sb,
+ const struct json_writer *jw)
+{
+ int k;
+ int eat_it = 0;
+
+ strbuf_reset(sb);
+ for (k = 0; k < jw->json.len; k++) {
+ char ch = jw->json.buf[k];
+ if (eat_it && ch == ' ')
+ continue;
+ if (ch == '\n') {
+ eat_it = 1;
+ continue;
+ }
+ eat_it = 0;
+ strbuf_addch(sb, ch);
+ }
+}
+
+static void append_sub_jw(struct json_writer *jw,
+ const struct json_writer *value)
+{
+ /*
+ * If both are pretty, increase the indentation of the sub_jw
+ * to better fit under the super.
+ *
+ * If the super is pretty, but the sub_jw is compact, leave the
+ * sub_jw compact. (We don't want to parse and rebuild the sub_jw
+ * for this debug-ish feature.)
+ *
+ * If the super is compact, and the sub_jw is pretty, convert
+ * the sub_jw to compact.
+ *
+ * If both are compact, keep the sub_jw compact.
+ */
+ if (jw->pretty && jw->open_stack.len && value->pretty) {
+ struct strbuf sb = STRBUF_INIT;
+ increase_indent(&sb, value, jw->open_stack.len * 2);
+ strbuf_addbuf(&jw->json, &sb);
+ strbuf_release(&sb);
+ return;
+ }
+ if (!jw->pretty && value->pretty) {
+ struct strbuf sb = STRBUF_INIT;
+ kill_indent(&sb, value);
+ strbuf_addbuf(&jw->json, &sb);
+ strbuf_release(&sb);
+ return;
+ }
+
+ strbuf_addbuf(&jw->json, &value->json);
+}
+
+/*
+ * Append existing (properly terminated) JSON sub-data (object or array)
+ * as-is onto the given JSON data.
+ */
+void jw_object_sub_jw(struct json_writer *jw, const char *key,
+ const struct json_writer *value)
+{
+ assert_is_terminated(value);
+
+ object_common(jw, key);
+ append_sub_jw(jw, value);
+}
+
+void jw_object_inline_begin_object(struct json_writer *jw, const char *key)
+{
+ object_common(jw, key);
+
+ jw_object_begin(jw, jw->pretty);
+}
+
+void jw_object_inline_begin_array(struct json_writer *jw, const char *key)
+{
+ object_common(jw, key);
+
+ jw_array_begin(jw, jw->pretty);
+}
+
+void jw_array_begin(struct json_writer *jw, int pretty)
+{
+ begin(jw, '[', pretty);
+}
+
+void jw_array_string(struct json_writer *jw, const char *value)
+{
+ array_common(jw);
+ append_quoted_string(&jw->json, value);
+}
+
+void jw_array_intmax(struct json_writer *jw, intmax_t value)
+{
+ array_common(jw);
+ strbuf_addf(&jw->json, "%"PRIdMAX, value);
+}
+
+void jw_array_double(struct json_writer *jw, int precision, double value)
+{
+ array_common(jw);
+ fmt_double(jw, precision, value);
+}
+
+void jw_array_true(struct json_writer *jw)
+{
+ array_common(jw);
+ strbuf_addstr(&jw->json, "true");
+}
+
+void jw_array_false(struct json_writer *jw)
+{
+ array_common(jw);
+ strbuf_addstr(&jw->json, "false");
+}
+
+void jw_array_bool(struct json_writer *jw, int value)
+{
+ if (value)
+ jw_array_true(jw);
+ else
+ jw_array_false(jw);
+}
+
+void jw_array_null(struct json_writer *jw)
+{
+ array_common(jw);
+ strbuf_addstr(&jw->json, "null");
+}
+
+void jw_array_sub_jw(struct json_writer *jw, const struct json_writer *value)
+{
+ assert_is_terminated(value);
+
+ array_common(jw);
+ append_sub_jw(jw, value);
+}
+
+void jw_array_argc_argv(struct json_writer *jw, int argc, const char **argv)
+{
+ int k;
+
+ for (k = 0; k < argc; k++)
+ jw_array_string(jw, argv[k]);
+}
+
+void jw_array_argv(struct json_writer *jw, const char **argv)
+{
+ while (*argv)
+ jw_array_string(jw, *argv++);
+}
+
+void jw_array_inline_begin_object(struct json_writer *jw)
+{
+ array_common(jw);
+
+ jw_object_begin(jw, jw->pretty);
+}
+
+void jw_array_inline_begin_array(struct json_writer *jw)
+{
+ array_common(jw);
+
+ jw_array_begin(jw, jw->pretty);
+}
+
+int jw_is_terminated(const struct json_writer *jw)
+{
+ return !jw->open_stack.len;
+}
+
+void jw_end(struct json_writer *jw)
+{
+ char ch_open;
+ int len;
+
+ if (!jw->open_stack.len)
+ BUG("json-writer: too many jw_end(): '%s'", jw->json.buf);
+
+ len = jw->open_stack.len - 1;
+ ch_open = jw->open_stack.buf[len];
+
+ strbuf_setlen(&jw->open_stack, len);
+ jw->need_comma = 1;
+
+ if (jw->pretty) {
+ strbuf_addch(&jw->json, '\n');
+ indent_pretty(jw);
+ }
+
+ if (ch_open == '{')
+ strbuf_addch(&jw->json, '}');
+ else
+ strbuf_addch(&jw->json, ']');
+}