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Diffstat (limited to 'src/markdown/md4c-html.c')
| -rw-r--r-- | src/markdown/md4c-html.c | 573 |
1 files changed, 573 insertions, 0 deletions
diff --git a/src/markdown/md4c-html.c b/src/markdown/md4c-html.c new file mode 100644 index 0000000..d604aec --- /dev/null +++ b/src/markdown/md4c-html.c @@ -0,0 +1,573 @@ +/* + * MD4C: Markdown parser for C + * (http://github.com/mity/md4c) + * + * Copyright (c) 2016-2019 Martin Mitas + * + * 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[] = { 0xef, 0xbf, 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 struct 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=\""); + + r->image_nesting_level++; +} + +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) ? "\" />" : "\">"); + + r->image_nesting_level--; +} + +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; + + if(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 becomes + * contents 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). + * + * This make-it-a-plain-text approach is the recommended practice by + * CommonMark specification (for HTML output). + */ + 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(r->image_nesting_level > 0) { + /* Ditto as in enter_span_callback(), except we have to allow the + * end of the <img> tag. */ + if(r->image_nesting_level == 1 && type == MD_SPAN_IMG) + render_close_img_span(r, (MD_SPAN_IMG_DETAIL*) detail); + 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: /*noop, handled above*/ 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] = { 0xef, 0xbb, 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); +} + |