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kc3-lang/md4c/src/md4c-html.c
Martin Mitas
- src/md4c-html.c
-
/* * MD4C: Markdown parser for C * (http://github.com/mity/md4c) * * Copyright (c) 2016-2024 Martin Mitáš * * Permission is hereby granted, free of charge, to any person obtaining a * copy of this software and associated documentation files (the "Software"), * to deal in the Software without restriction, including without limitation * the rights to use, copy, modify, merge, publish, distribute, sublicense, * and/or sell copies of the Software, and to permit persons to whom the * Software is furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS * IN THE SOFTWARE. */ #include <stdio.h> #include <string.h> #include "md4c-html.h" #include "entity.h" #if !defined(__STDC_VERSION__) || __STDC_VERSION__ < 199409L /* C89/90 or old compilers in general may not understand "inline". */ #if defined __GNUC__ #define inline __inline__ #elif defined _MSC_VER #define inline __inline #else #define inline #endif #endif #ifdef _WIN32 #define snprintf _snprintf #endif typedef struct MD_HTML_tag MD_HTML; struct MD_HTML_tag { void (*process_output)(const MD_CHAR*, MD_SIZE, void*); void* userdata; unsigned flags; int image_nesting_level; char escape_map[256]; }; #define NEED_HTML_ESC_FLAG 0x1 #define NEED_URL_ESC_FLAG 0x2 /***************************************** *** HTML rendering helper functions *** *****************************************/ #define ISDIGIT(ch) ('0' <= (ch) && (ch) <= '9') #define ISLOWER(ch) ('a' <= (ch) && (ch) <= 'z') #define ISUPPER(ch) ('A' <= (ch) && (ch) <= 'Z') #define ISALNUM(ch) (ISLOWER(ch) || ISUPPER(ch) || ISDIGIT(ch)) static inline void render_verbatim(MD_HTML* r, const MD_CHAR* text, MD_SIZE size) { r->process_output(text, size, r->userdata); } /* Keep this as a macro. Most compiler should then be smart enough to replace * the strlen() call with a compile-time constant if the string is a C literal. */ #define RENDER_VERBATIM(r, verbatim) \ render_verbatim((r), (verbatim), (MD_SIZE) (strlen(verbatim))) static void render_html_escaped(MD_HTML* r, const MD_CHAR* data, MD_SIZE size) { MD_OFFSET beg = 0; MD_OFFSET off = 0; /* Some characters need to be escaped in normal HTML text. */ #define NEED_HTML_ESC(ch) (r->escape_map[(unsigned char)(ch)] & NEED_HTML_ESC_FLAG) while(1) { /* Optimization: Use some loop unrolling. */ while(off + 3 < size && !NEED_HTML_ESC(data[off+0]) && !NEED_HTML_ESC(data[off+1]) && !NEED_HTML_ESC(data[off+2]) && !NEED_HTML_ESC(data[off+3])) off += 4; while(off < size && !NEED_HTML_ESC(data[off])) off++; if(off > beg) render_verbatim(r, data + beg, off - beg); if(off < size) { switch(data[off]) { case '&': RENDER_VERBATIM(r, "&"); break; case '<': RENDER_VERBATIM(r, "<"); break; case '>': RENDER_VERBATIM(r, ">"); break; case '"': RENDER_VERBATIM(r, """); break; } off++; } else { break; } beg = off; } } static void render_url_escaped(MD_HTML* r, const MD_CHAR* data, MD_SIZE size) { static const MD_CHAR hex_chars[] = "0123456789ABCDEF"; MD_OFFSET beg = 0; MD_OFFSET off = 0; /* Some characters need to be escaped in URL attributes. */ #define NEED_URL_ESC(ch) (r->escape_map[(unsigned char)(ch)] & NEED_URL_ESC_FLAG) while(1) { while(off < size && !NEED_URL_ESC(data[off])) off++; if(off > beg) render_verbatim(r, data + beg, off - beg); if(off < size) { char hex[3]; switch(data[off]) { case '&': RENDER_VERBATIM(r, "&"); break; default: hex[0] = '%'; hex[1] = hex_chars[((unsigned)data[off] >> 4) & 0xf]; hex[2] = hex_chars[((unsigned)data[off] >> 0) & 0xf]; render_verbatim(r, hex, 3); break; } off++; } else { break; } beg = off; } } static unsigned hex_val(char ch) { if('0' <= ch && ch <= '9') return ch - '0'; if('A' <= ch && ch <= 'Z') return ch - 'A' + 10; else return ch - 'a' + 10; } static void render_utf8_codepoint(MD_HTML* r, unsigned codepoint, void (*fn_append)(MD_HTML*, const MD_CHAR*, MD_SIZE)) { static const MD_CHAR utf8_replacement_char[] = { (char)0xef, (char)0xbf, (char)0xbd }; unsigned char utf8[4]; size_t n; if(codepoint <= 0x7f) { n = 1; utf8[0] = codepoint; } else if(codepoint <= 0x7ff) { n = 2; utf8[0] = 0xc0 | ((codepoint >> 6) & 0x1f); utf8[1] = 0x80 + ((codepoint >> 0) & 0x3f); } else if(codepoint <= 0xffff) { n = 3; utf8[0] = 0xe0 | ((codepoint >> 12) & 0xf); utf8[1] = 0x80 + ((codepoint >> 6) & 0x3f); utf8[2] = 0x80 + ((codepoint >> 0) & 0x3f); } else { n = 4; utf8[0] = 0xf0 | ((codepoint >> 18) & 0x7); utf8[1] = 0x80 + ((codepoint >> 12) & 0x3f); utf8[2] = 0x80 + ((codepoint >> 6) & 0x3f); utf8[3] = 0x80 + ((codepoint >> 0) & 0x3f); } if(0 < codepoint && codepoint <= 0x10ffff) fn_append(r, (char*)utf8, (MD_SIZE)n); else fn_append(r, utf8_replacement_char, 3); } /* Translate entity to its UTF-8 equivalent, or output the verbatim one * if such entity is unknown (or if the translation is disabled). */ static void render_entity(MD_HTML* r, const MD_CHAR* text, MD_SIZE size, void (*fn_append)(MD_HTML*, const MD_CHAR*, MD_SIZE)) { if(r->flags & MD_HTML_FLAG_VERBATIM_ENTITIES) { render_verbatim(r, text, size); return; } /* We assume UTF-8 output is what is desired. */ if(size > 3 && text[1] == '#') { unsigned codepoint = 0; if(text[2] == 'x' || text[2] == 'X') { /* Hexadecimal entity (e.g. "�")). */ MD_SIZE i; for(i = 3; i < size-1; i++) codepoint = 16 * codepoint + hex_val(text[i]); } else { /* Decimal entity (e.g. "&1234;") */ MD_SIZE i; for(i = 2; i < size-1; i++) codepoint = 10 * codepoint + (text[i] - '0'); } render_utf8_codepoint(r, codepoint, fn_append); return; } else { /* Named entity (e.g. " "). */ const ENTITY* ent; ent = entity_lookup(text, size); if(ent != NULL) { render_utf8_codepoint(r, ent->codepoints[0], fn_append); if(ent->codepoints[1]) render_utf8_codepoint(r, ent->codepoints[1], fn_append); return; } } fn_append(r, text, size); } static void render_attribute(MD_HTML* r, const MD_ATTRIBUTE* attr, void (*fn_append)(MD_HTML*, const MD_CHAR*, MD_SIZE)) { int i; for(i = 0; attr->substr_offsets[i] < attr->size; i++) { MD_TEXTTYPE type = attr->substr_types[i]; MD_OFFSET off = attr->substr_offsets[i]; MD_SIZE size = attr->substr_offsets[i+1] - off; const MD_CHAR* text = attr->text + off; switch(type) { case MD_TEXT_NULLCHAR: render_utf8_codepoint(r, 0x0000, render_verbatim); break; case MD_TEXT_ENTITY: render_entity(r, text, size, fn_append); break; default: fn_append(r, text, size); break; } } } static void render_open_ol_block(MD_HTML* r, const MD_BLOCK_OL_DETAIL* det) { char buf[64]; if(det->start == 1) { RENDER_VERBATIM(r, "<ol>\n"); return; } snprintf(buf, sizeof(buf), "<ol start=\"%u\">\n", det->start); RENDER_VERBATIM(r, buf); } static void render_open_li_block(MD_HTML* r, const MD_BLOCK_LI_DETAIL* det) { if(det->is_task) { RENDER_VERBATIM(r, "<li class=\"task-list-item\">" "<input type=\"checkbox\" class=\"task-list-item-checkbox\" disabled"); if(det->task_mark == 'x' || det->task_mark == 'X') RENDER_VERBATIM(r, " checked"); RENDER_VERBATIM(r, ">"); } else { RENDER_VERBATIM(r, "<li>"); } } static void render_open_code_block(MD_HTML* r, const MD_BLOCK_CODE_DETAIL* det) { RENDER_VERBATIM(r, "<pre><code"); /* If known, output the HTML 5 attribute class="language-LANGNAME". */ if(det->lang.text != NULL) { RENDER_VERBATIM(r, " class=\"language-"); render_attribute(r, &det->lang, render_html_escaped); RENDER_VERBATIM(r, "\""); } RENDER_VERBATIM(r, ">"); } static void render_open_td_block(MD_HTML* r, const MD_CHAR* cell_type, const MD_BLOCK_TD_DETAIL* det) { RENDER_VERBATIM(r, "<"); RENDER_VERBATIM(r, cell_type); switch(det->align) { case MD_ALIGN_LEFT: RENDER_VERBATIM(r, " align=\"left\">"); break; case MD_ALIGN_CENTER: RENDER_VERBATIM(r, " align=\"center\">"); break; case MD_ALIGN_RIGHT: RENDER_VERBATIM(r, " align=\"right\">"); break; default: RENDER_VERBATIM(r, ">"); break; } } static void render_open_a_span(MD_HTML* r, const MD_SPAN_A_DETAIL* det) { RENDER_VERBATIM(r, "<a href=\""); render_attribute(r, &det->href, render_url_escaped); if(det->title.text != NULL) { RENDER_VERBATIM(r, "\" title=\""); render_attribute(r, &det->title, render_html_escaped); } RENDER_VERBATIM(r, "\">"); } static void render_open_img_span(MD_HTML* r, const MD_SPAN_IMG_DETAIL* det) { RENDER_VERBATIM(r, "<img src=\""); render_attribute(r, &det->src, render_url_escaped); RENDER_VERBATIM(r, "\" alt=\""); } static void render_close_img_span(MD_HTML* r, const MD_SPAN_IMG_DETAIL* det) { if(det->title.text != NULL) { RENDER_VERBATIM(r, "\" title=\""); render_attribute(r, &det->title, render_html_escaped); } RENDER_VERBATIM(r, (r->flags & MD_HTML_FLAG_XHTML) ? "\" />" : "\">"); } static void render_open_wikilink_span(MD_HTML* r, const MD_SPAN_WIKILINK_DETAIL* det) { RENDER_VERBATIM(r, "<x-wikilink data-target=\""); render_attribute(r, &det->target, render_html_escaped); RENDER_VERBATIM(r, "\">"); } /************************************** *** HTML renderer implementation *** **************************************/ static int enter_block_callback(MD_BLOCKTYPE type, void* detail, void* userdata) { static const MD_CHAR* head[6] = { "<h1>", "<h2>", "<h3>", "<h4>", "<h5>", "<h6>" }; MD_HTML* r = (MD_HTML*) userdata; switch(type) { case MD_BLOCK_DOC: /* noop */ break; case MD_BLOCK_QUOTE: RENDER_VERBATIM(r, "<blockquote>\n"); break; case MD_BLOCK_UL: RENDER_VERBATIM(r, "<ul>\n"); break; case MD_BLOCK_OL: render_open_ol_block(r, (const MD_BLOCK_OL_DETAIL*)detail); break; case MD_BLOCK_LI: render_open_li_block(r, (const MD_BLOCK_LI_DETAIL*)detail); break; case MD_BLOCK_HR: RENDER_VERBATIM(r, (r->flags & MD_HTML_FLAG_XHTML) ? "<hr />\n" : "<hr>\n"); break; case MD_BLOCK_H: RENDER_VERBATIM(r, head[((MD_BLOCK_H_DETAIL*)detail)->level - 1]); break; case MD_BLOCK_CODE: render_open_code_block(r, (const MD_BLOCK_CODE_DETAIL*) detail); break; case MD_BLOCK_HTML: /* noop */ break; case MD_BLOCK_P: RENDER_VERBATIM(r, "<p>"); break; case MD_BLOCK_TABLE: RENDER_VERBATIM(r, "<table>\n"); break; case MD_BLOCK_THEAD: RENDER_VERBATIM(r, "<thead>\n"); break; case MD_BLOCK_TBODY: RENDER_VERBATIM(r, "<tbody>\n"); break; case MD_BLOCK_TR: RENDER_VERBATIM(r, "<tr>\n"); break; case MD_BLOCK_TH: render_open_td_block(r, "th", (MD_BLOCK_TD_DETAIL*)detail); break; case MD_BLOCK_TD: render_open_td_block(r, "td", (MD_BLOCK_TD_DETAIL*)detail); break; } return 0; } static int leave_block_callback(MD_BLOCKTYPE type, void* detail, void* userdata) { static const MD_CHAR* head[6] = { "</h1>\n", "</h2>\n", "</h3>\n", "</h4>\n", "</h5>\n", "</h6>\n" }; MD_HTML* r = (MD_HTML*) userdata; switch(type) { case MD_BLOCK_DOC: /*noop*/ break; case MD_BLOCK_QUOTE: RENDER_VERBATIM(r, "</blockquote>\n"); break; case MD_BLOCK_UL: RENDER_VERBATIM(r, "</ul>\n"); break; case MD_BLOCK_OL: RENDER_VERBATIM(r, "</ol>\n"); break; case MD_BLOCK_LI: RENDER_VERBATIM(r, "</li>\n"); break; case MD_BLOCK_HR: /*noop*/ break; case MD_BLOCK_H: RENDER_VERBATIM(r, head[((MD_BLOCK_H_DETAIL*)detail)->level - 1]); break; case MD_BLOCK_CODE: RENDER_VERBATIM(r, "</code></pre>\n"); break; case MD_BLOCK_HTML: /* noop */ break; case MD_BLOCK_P: RENDER_VERBATIM(r, "</p>\n"); break; case MD_BLOCK_TABLE: RENDER_VERBATIM(r, "</table>\n"); break; case MD_BLOCK_THEAD: RENDER_VERBATIM(r, "</thead>\n"); break; case MD_BLOCK_TBODY: RENDER_VERBATIM(r, "</tbody>\n"); break; case MD_BLOCK_TR: RENDER_VERBATIM(r, "</tr>\n"); break; case MD_BLOCK_TH: RENDER_VERBATIM(r, "</th>\n"); break; case MD_BLOCK_TD: RENDER_VERBATIM(r, "</td>\n"); break; } return 0; } static int enter_span_callback(MD_SPANTYPE type, void* detail, void* userdata) { MD_HTML* r = (MD_HTML*) userdata; int inside_img = (r->image_nesting_level > 0); /* We are inside a Markdown image label. Markdown allows to use any emphasis * and other rich contents in that context similarly as in any link label. * * However, unlike in the case of links (where that contents becomescontents * of the <a>...</a> tag), in the case of images the contents is supposed to * fall into the attribute alt: <img alt="...">. * * In that context we naturally cannot output nested HTML tags. So lets * suppress them and only output the plain text (i.e. what falls into text() * callback). * * CommonMark specification declares this a recommended practice for HTML * output. */ if(type == MD_SPAN_IMG) r->image_nesting_level++; if(inside_img) return 0; switch(type) { case MD_SPAN_EM: RENDER_VERBATIM(r, "<em>"); break; case MD_SPAN_STRONG: RENDER_VERBATIM(r, "<strong>"); break; case MD_SPAN_U: RENDER_VERBATIM(r, "<u>"); break; case MD_SPAN_A: render_open_a_span(r, (MD_SPAN_A_DETAIL*) detail); break; case MD_SPAN_IMG: render_open_img_span(r, (MD_SPAN_IMG_DETAIL*) detail); break; case MD_SPAN_CODE: RENDER_VERBATIM(r, "<code>"); break; case MD_SPAN_DEL: RENDER_VERBATIM(r, "<del>"); break; case MD_SPAN_LATEXMATH: RENDER_VERBATIM(r, "<x-equation>"); break; case MD_SPAN_LATEXMATH_DISPLAY: RENDER_VERBATIM(r, "<x-equation type=\"display\">"); break; case MD_SPAN_WIKILINK: render_open_wikilink_span(r, (MD_SPAN_WIKILINK_DETAIL*) detail); break; } return 0; } static int leave_span_callback(MD_SPANTYPE type, void* detail, void* userdata) { MD_HTML* r = (MD_HTML*) userdata; if(type == MD_SPAN_IMG) r->image_nesting_level--; if(r->image_nesting_level > 0) return 0; switch(type) { case MD_SPAN_EM: RENDER_VERBATIM(r, "</em>"); break; case MD_SPAN_STRONG: RENDER_VERBATIM(r, "</strong>"); break; case MD_SPAN_U: RENDER_VERBATIM(r, "</u>"); break; case MD_SPAN_A: RENDER_VERBATIM(r, "</a>"); break; case MD_SPAN_IMG: render_close_img_span(r, (MD_SPAN_IMG_DETAIL*) detail); break; case MD_SPAN_CODE: RENDER_VERBATIM(r, "</code>"); break; case MD_SPAN_DEL: RENDER_VERBATIM(r, "</del>"); break; case MD_SPAN_LATEXMATH: /*fall through*/ case MD_SPAN_LATEXMATH_DISPLAY: RENDER_VERBATIM(r, "</x-equation>"); break; case MD_SPAN_WIKILINK: RENDER_VERBATIM(r, "</x-wikilink>"); break; } return 0; } static int text_callback(MD_TEXTTYPE type, const MD_CHAR* text, MD_SIZE size, void* userdata) { MD_HTML* r = (MD_HTML*) userdata; switch(type) { case MD_TEXT_NULLCHAR: render_utf8_codepoint(r, 0x0000, render_verbatim); break; case MD_TEXT_BR: RENDER_VERBATIM(r, (r->image_nesting_level == 0 ? ((r->flags & MD_HTML_FLAG_XHTML) ? "<br />\n" : "<br>\n") : " ")); break; case MD_TEXT_SOFTBR: RENDER_VERBATIM(r, (r->image_nesting_level == 0 ? "\n" : " ")); break; case MD_TEXT_HTML: render_verbatim(r, text, size); break; case MD_TEXT_ENTITY: render_entity(r, text, size, render_html_escaped); break; default: render_html_escaped(r, text, size); break; } return 0; } static void debug_log_callback(const char* msg, void* userdata) { MD_HTML* r = (MD_HTML*) userdata; if(r->flags & MD_HTML_FLAG_DEBUG) fprintf(stderr, "MD4C: %s\n", msg); } int md_html(const MD_CHAR* input, MD_SIZE input_size, void (*process_output)(const MD_CHAR*, MD_SIZE, void*), void* userdata, unsigned parser_flags, unsigned renderer_flags) { MD_HTML render = { process_output, userdata, renderer_flags, 0, { 0 } }; int i; MD_PARSER parser = { 0, parser_flags, enter_block_callback, leave_block_callback, enter_span_callback, leave_span_callback, text_callback, debug_log_callback, NULL }; /* Build map of characters which need escaping. */ for(i = 0; i < 256; i++) { unsigned char ch = (unsigned char) i; if(strchr("\"&<>", ch) != NULL) render.escape_map[i] |= NEED_HTML_ESC_FLAG; if(!ISALNUM(ch) && strchr("~-_.+!*(),%#@?=;:/,+$", ch) == NULL) render.escape_map[i] |= NEED_URL_ESC_FLAG; } /* Consider skipping UTF-8 byte order mark (BOM). */ if(renderer_flags & MD_HTML_FLAG_SKIP_UTF8_BOM && sizeof(MD_CHAR) == 1) { static const MD_CHAR bom[3] = { (char)0xef, (char)0xbb, (char)0xbf }; if(input_size >= sizeof(bom) && memcmp(input, bom, sizeof(bom)) == 0) { input += sizeof(bom); input_size -= sizeof(bom); } } return md_parse(input, input_size, &parser, (void*) &render); }