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75459410ed
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>
414 lines
8.5 KiB
C
414 lines
8.5 KiB
C
#include "cache.h"
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#include "json-writer.h"
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void jw_init(struct json_writer *jw)
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{
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strbuf_init(&jw->json, 0);
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strbuf_init(&jw->open_stack, 0);
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jw->need_comma = 0;
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jw->pretty = 0;
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}
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void jw_release(struct json_writer *jw)
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{
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strbuf_release(&jw->json);
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strbuf_release(&jw->open_stack);
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}
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/*
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* Append JSON-quoted version of the given string to 'out'.
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*/
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static void append_quoted_string(struct strbuf *out, const char *in)
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{
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unsigned char c;
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strbuf_addch(out, '"');
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while ((c = *in++) != '\0') {
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if (c == '"')
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strbuf_addstr(out, "\\\"");
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else if (c == '\\')
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strbuf_addstr(out, "\\\\");
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else if (c == '\n')
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strbuf_addstr(out, "\\n");
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else if (c == '\r')
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strbuf_addstr(out, "\\r");
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else if (c == '\t')
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strbuf_addstr(out, "\\t");
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else if (c == '\f')
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strbuf_addstr(out, "\\f");
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else if (c == '\b')
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strbuf_addstr(out, "\\b");
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else if (c < 0x20)
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strbuf_addf(out, "\\u%04x", c);
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else
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strbuf_addch(out, c);
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}
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strbuf_addch(out, '"');
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}
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static void indent_pretty(struct json_writer *jw)
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{
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int k;
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for (k = 0; k < jw->open_stack.len; k++)
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strbuf_addstr(&jw->json, " ");
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}
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/*
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* Begin an object or array (either top-level or nested within the currently
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* open object or array).
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*/
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static void begin(struct json_writer *jw, char ch_open, int pretty)
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{
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jw->pretty = pretty;
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strbuf_addch(&jw->json, ch_open);
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strbuf_addch(&jw->open_stack, ch_open);
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jw->need_comma = 0;
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}
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/*
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* Assert that the top of the open-stack is an object.
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*/
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static void assert_in_object(const struct json_writer *jw, const char *key)
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{
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if (!jw->open_stack.len)
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BUG("json-writer: object: missing jw_object_begin(): '%s'", key);
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if (jw->open_stack.buf[jw->open_stack.len - 1] != '{')
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BUG("json-writer: object: not in object: '%s'", key);
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}
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/*
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* Assert that the top of the open-stack is an array.
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*/
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static void assert_in_array(const struct json_writer *jw)
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{
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if (!jw->open_stack.len)
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BUG("json-writer: array: missing jw_array_begin()");
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if (jw->open_stack.buf[jw->open_stack.len - 1] != '[')
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BUG("json-writer: array: not in array");
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}
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/*
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* Add comma if we have already seen a member at this level.
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*/
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static void maybe_add_comma(struct json_writer *jw)
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{
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if (jw->need_comma)
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strbuf_addch(&jw->json, ',');
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else
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jw->need_comma = 1;
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}
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static void fmt_double(struct json_writer *jw, int precision,
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double value)
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{
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if (precision < 0) {
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strbuf_addf(&jw->json, "%f", value);
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} else {
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struct strbuf fmt = STRBUF_INIT;
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strbuf_addf(&fmt, "%%.%df", precision);
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strbuf_addf(&jw->json, fmt.buf, value);
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strbuf_release(&fmt);
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}
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}
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static void object_common(struct json_writer *jw, const char *key)
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{
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assert_in_object(jw, key);
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maybe_add_comma(jw);
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if (jw->pretty) {
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strbuf_addch(&jw->json, '\n');
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indent_pretty(jw);
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}
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append_quoted_string(&jw->json, key);
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strbuf_addch(&jw->json, ':');
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if (jw->pretty)
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strbuf_addch(&jw->json, ' ');
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}
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static void array_common(struct json_writer *jw)
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{
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assert_in_array(jw);
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maybe_add_comma(jw);
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if (jw->pretty) {
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strbuf_addch(&jw->json, '\n');
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indent_pretty(jw);
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}
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}
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/*
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* Assert that the given JSON object or JSON array has been properly
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* terminated. (Has closing bracket.)
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*/
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static void assert_is_terminated(const struct json_writer *jw)
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{
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if (jw->open_stack.len)
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BUG("json-writer: object: missing jw_end(): '%s'",
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jw->json.buf);
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}
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void jw_object_begin(struct json_writer *jw, int pretty)
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{
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begin(jw, '{', pretty);
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}
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void jw_object_string(struct json_writer *jw, const char *key, const char *value)
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{
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object_common(jw, key);
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append_quoted_string(&jw->json, value);
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}
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void jw_object_intmax(struct json_writer *jw, const char *key, intmax_t value)
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{
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object_common(jw, key);
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strbuf_addf(&jw->json, "%"PRIdMAX, value);
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}
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void jw_object_double(struct json_writer *jw, const char *key, int precision,
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double value)
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{
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object_common(jw, key);
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fmt_double(jw, precision, value);
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}
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void jw_object_true(struct json_writer *jw, const char *key)
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{
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object_common(jw, key);
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strbuf_addstr(&jw->json, "true");
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}
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void jw_object_false(struct json_writer *jw, const char *key)
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{
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object_common(jw, key);
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strbuf_addstr(&jw->json, "false");
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}
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void jw_object_bool(struct json_writer *jw, const char *key, int value)
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{
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if (value)
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jw_object_true(jw, key);
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else
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jw_object_false(jw, key);
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}
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void jw_object_null(struct json_writer *jw, const char *key)
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{
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object_common(jw, key);
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strbuf_addstr(&jw->json, "null");
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}
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static void increase_indent(struct strbuf *sb,
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const struct json_writer *jw,
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int indent)
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{
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int k;
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strbuf_reset(sb);
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for (k = 0; k < jw->json.len; k++) {
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char ch = jw->json.buf[k];
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strbuf_addch(sb, ch);
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if (ch == '\n')
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strbuf_addchars(sb, ' ', indent);
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}
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}
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static void kill_indent(struct strbuf *sb,
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const struct json_writer *jw)
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{
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int k;
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int eat_it = 0;
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strbuf_reset(sb);
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for (k = 0; k < jw->json.len; k++) {
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char ch = jw->json.buf[k];
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if (eat_it && ch == ' ')
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continue;
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if (ch == '\n') {
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eat_it = 1;
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continue;
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}
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eat_it = 0;
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strbuf_addch(sb, ch);
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}
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}
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static void append_sub_jw(struct json_writer *jw,
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const struct json_writer *value)
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{
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/*
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* If both are pretty, increase the indentation of the sub_jw
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* to better fit under the super.
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*
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* If the super is pretty, but the sub_jw is compact, leave the
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* sub_jw compact. (We don't want to parse and rebuild the sub_jw
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* for this debug-ish feature.)
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*
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* If the super is compact, and the sub_jw is pretty, convert
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* the sub_jw to compact.
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*
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* If both are compact, keep the sub_jw compact.
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*/
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if (jw->pretty && jw->open_stack.len && value->pretty) {
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struct strbuf sb = STRBUF_INIT;
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increase_indent(&sb, value, jw->open_stack.len * 2);
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strbuf_addbuf(&jw->json, &sb);
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strbuf_release(&sb);
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return;
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}
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if (!jw->pretty && value->pretty) {
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struct strbuf sb = STRBUF_INIT;
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kill_indent(&sb, value);
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strbuf_addbuf(&jw->json, &sb);
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strbuf_release(&sb);
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return;
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}
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strbuf_addbuf(&jw->json, &value->json);
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}
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/*
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* Append existing (properly terminated) JSON sub-data (object or array)
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* as-is onto the given JSON data.
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*/
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void jw_object_sub_jw(struct json_writer *jw, const char *key,
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const struct json_writer *value)
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{
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assert_is_terminated(value);
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object_common(jw, key);
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append_sub_jw(jw, value);
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}
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void jw_object_inline_begin_object(struct json_writer *jw, const char *key)
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{
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object_common(jw, key);
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jw_object_begin(jw, jw->pretty);
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}
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void jw_object_inline_begin_array(struct json_writer *jw, const char *key)
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{
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object_common(jw, key);
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jw_array_begin(jw, jw->pretty);
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}
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void jw_array_begin(struct json_writer *jw, int pretty)
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{
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begin(jw, '[', pretty);
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}
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void jw_array_string(struct json_writer *jw, const char *value)
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{
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array_common(jw);
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append_quoted_string(&jw->json, value);
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}
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void jw_array_intmax(struct json_writer *jw, intmax_t value)
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{
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array_common(jw);
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strbuf_addf(&jw->json, "%"PRIdMAX, value);
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}
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void jw_array_double(struct json_writer *jw, int precision, double value)
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{
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array_common(jw);
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fmt_double(jw, precision, value);
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}
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void jw_array_true(struct json_writer *jw)
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{
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array_common(jw);
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strbuf_addstr(&jw->json, "true");
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}
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void jw_array_false(struct json_writer *jw)
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{
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array_common(jw);
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strbuf_addstr(&jw->json, "false");
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}
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void jw_array_bool(struct json_writer *jw, int value)
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{
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if (value)
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jw_array_true(jw);
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else
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jw_array_false(jw);
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}
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void jw_array_null(struct json_writer *jw)
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{
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array_common(jw);
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strbuf_addstr(&jw->json, "null");
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}
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void jw_array_sub_jw(struct json_writer *jw, const struct json_writer *value)
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{
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assert_is_terminated(value);
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array_common(jw);
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append_sub_jw(jw, value);
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}
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void jw_array_argc_argv(struct json_writer *jw, int argc, const char **argv)
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{
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int k;
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for (k = 0; k < argc; k++)
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jw_array_string(jw, argv[k]);
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}
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void jw_array_argv(struct json_writer *jw, const char **argv)
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{
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while (*argv)
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jw_array_string(jw, *argv++);
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}
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void jw_array_inline_begin_object(struct json_writer *jw)
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{
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array_common(jw);
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jw_object_begin(jw, jw->pretty);
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}
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void jw_array_inline_begin_array(struct json_writer *jw)
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{
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array_common(jw);
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jw_array_begin(jw, jw->pretty);
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}
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int jw_is_terminated(const struct json_writer *jw)
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{
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return !jw->open_stack.len;
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}
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void jw_end(struct json_writer *jw)
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{
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char ch_open;
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int len;
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if (!jw->open_stack.len)
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BUG("json-writer: too many jw_end(): '%s'", jw->json.buf);
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len = jw->open_stack.len - 1;
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ch_open = jw->open_stack.buf[len];
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strbuf_setlen(&jw->open_stack, len);
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jw->need_comma = 1;
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if (jw->pretty) {
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strbuf_addch(&jw->json, '\n');
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indent_pretty(jw);
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}
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if (ch_open == '{')
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strbuf_addch(&jw->json, '}');
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else
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strbuf_addch(&jw->json, ']');
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}
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