path: root/src/html.c

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <assert.h>

#include "config.h"
#include "cmark.h"
#include "node.h"
#include "buffer.h"
#include "houdini.h"

// Functions to convert cmark_nodes to HTML strings.

static bool
finish_node(strbuf *html, cmark_node *node, bool tight);

static void escape_html(strbuf *dest, const unsigned char *source, int length)
{
    if (length < 0)
        length = strlen((char *)source);

    houdini_escape_html0(dest, source, (size_t)length, 0);
}

static void escape_href(strbuf *dest, const unsigned char *source, int length)
{
    if (length < 0)
        length = strlen((char *)source);

    houdini_escape_href(dest, source, (size_t)length);
}

static inline void cr(strbuf *html)
{
    if (html->size && html->ptr[html->size - 1] != '\n')
        strbuf_putc(html, '\n');
}

// Convert the inline children of a node to a plain string.
static void inlines_to_plain_html(strbuf *html, cmark_node* node)
{
    cmark_node* cur = node->first_child;

    if (cur == NULL) {
        return;
    }

    while (true) {
        switch(cur->type) {
        case NODE_TEXT:
        case NODE_INLINE_CODE:
        case NODE_INLINE_HTML:
            escape_html(html, cur->as.literal.data, cur->as.literal.len);
            break;

        case NODE_LINEBREAK:
        case NODE_SOFTBREAK:
            strbuf_putc(html, ' ');
            break;

        default:
            break;
        }

        if (cur->first_child) {
            cur = cur->first_child;
            continue;
        }

    next_sibling:
        if (cur->next) {
            cur = cur->next;
            continue;
        }
        cur = cur->parent;
        if (cur == node) {
            break;
        }
        goto next_sibling;
    }
}


// Convert a cmark_node to HTML.
static void node_to_html(strbuf *html, cmark_node *node)
{
    cmark_node *cur;
    char start_header[] = "<h0>";
    bool tight = false;
    bool visit_children;
    strbuf *info;

    if (node == NULL) {
        return;
    }

    cur = node;
    while (true) {
        // Only NODE_IMAGE wants to skip its children.
        visit_children = true;

        switch(cur->type) {
        case NODE_DOCUMENT:
            break;

        case NODE_PARAGRAPH:
            if (!tight) {
                cr(html);
                strbuf_puts(html, "<p>");
            }
            break;

        case NODE_BLOCK_QUOTE:
            cr(html);
            strbuf_puts(html, "<blockquote>\n");
            // BLOCK_QUOTE doesn't use any of the 'as' structs,
            // so the 'list' member can be used to store the
            // current value of 'tight'.
            cur->as.list.tight = tight;
            tight = false;
            break;

        case NODE_LIST_ITEM:
            cr(html);
            strbuf_puts(html, "<li>");
            break;

        case NODE_LIST: {
            cmark_list *list = &cur->as.list;
            bool tmp;

            // make sure a list starts at the beginning of the line:
            cr(html);

            if (list->list_type == CMARK_BULLET_LIST) {
                strbuf_puts(html, "<ul>\n");
            }
            else if (list->start == 1) {
                strbuf_puts(html, "<ol>\n");
            }
            else {
                strbuf_printf(html, "<ol start=\"%d\">\n",
                          list->start);
            }

            // Store the current value of 'tight' by swapping.
            tmp = list->tight;
            list->tight = tight;
            tight = tmp;
            break;
        }

        case NODE_HEADER:
            cr(html);
            start_header[2] = '0' + cur->as.header.level;
            strbuf_puts(html, start_header);
            break;

        case NODE_CODE_BLOCK:
            info = &cur->as.code.info;
            cr(html);

            if (&cur->as.code.fence_length == 0
                || strbuf_len(info) == 0) {
                strbuf_puts(html, "<pre><code>");
            }
            else {
                int first_tag = strbuf_strchr(info, ' ', 0);
                if (first_tag < 0)
                    first_tag = strbuf_len(info);

                strbuf_puts(html,
                        "<pre><code class=\"language-");
                escape_html(html, info->ptr, first_tag);
                strbuf_puts(html, "\">");
            }

            escape_html(html, cur->string_content.ptr, cur->string_content.size);
            break;

        case NODE_HTML:
            cr(html);
            strbuf_put(html, cur->string_content.ptr, cur->string_content.size);
            break;

        case NODE_HRULE:
            cr(html);
            strbuf_puts(html, "<hr />\n");
            break;

        case NODE_REFERENCE_DEF:
            break;

        case NODE_TEXT:
            escape_html(html, cur->as.literal.data, cur->as.literal.len);
            break;

        case NODE_LINEBREAK:
            strbuf_puts(html, "<br />\n");
            break;

        case NODE_SOFTBREAK:
            strbuf_putc(html, '\n');
            break;

        case NODE_INLINE_CODE:
            strbuf_puts(html, "<code>");
            escape_html(html, cur->as.literal.data, cur->as.literal.len);
            break;

        case NODE_INLINE_HTML:
            strbuf_put(html,
                   cur->as.literal.data,
                   cur->as.literal.len);
            break;

        case NODE_LINK:
            strbuf_puts(html, "<a href=\"");
            if (cur->as.link.url)
                escape_href(html, cur->as.link.url, -1);

            if (cur->as.link.title) {
                strbuf_puts(html, "\" title=\"");
                escape_html(html, cur->as.link.title, -1);
            }

            strbuf_puts(html, "\">");
            break;

        case NODE_IMAGE:
            strbuf_puts(html, "<img src=\"");
            if (cur->as.link.url)
                escape_href(html, cur->as.link.url, -1);

            strbuf_puts(html, "\" alt=\"");
            inlines_to_plain_html(html, cur);

            if (cur->as.link.title) {
                strbuf_puts(html, "\" title=\"");
                escape_html(html, cur->as.link.title, -1);
            }

            strbuf_puts(html, "\" />");
            visit_children = false;
            break;

        case NODE_STRONG:
            strbuf_puts(html, "<strong>");
            break;

        case NODE_EMPH:
            strbuf_puts(html, "<em>");
            break;

        default:
            assert(false);
        }

        if (visit_children && cur->first_child) {
            cur = cur->first_child;
            continue;
        }

    next_sibling:
        tight = finish_node(html, cur, tight);
        if (cur == node) {
            break;
        }
        if (cur->next) {
            cur = cur->next;
            continue;
        }
        cur = cur->parent;
        goto next_sibling;
    }
}

// Returns the restored value of 'tight'.
static bool
finish_node(strbuf *html, cmark_node *node, bool tight)
{
    char end_header[] = "</h0>\n";

    switch (node->type) {
    case NODE_PARAGRAPH:
        if (!tight) {
            strbuf_puts(html, "</p>\n");
        }
        break;

    case NODE_BLOCK_QUOTE: {
        cmark_list *list = &node->as.list;
        strbuf_puts(html, "</blockquote>\n");
        // Restore old 'tight' value.
        tight = list->tight;
        list->tight = false;
        break;
    }

    case NODE_LIST_ITEM:
        strbuf_puts(html, "</li>\n");
        break;

    case NODE_LIST: {
        cmark_list *list = &node->as.list;
        bool tmp;
        strbuf_puts(html,
                list->list_type == CMARK_BULLET_LIST ?
                "</ul>\n" : "</ol>\n");
        // Restore old 'tight' value.
        tmp = tight;
        tight = list->tight;
        list->tight = tmp;
        break;
    }

    case NODE_HEADER:
        end_header[3] = '0' + node->as.header.level;
        strbuf_puts(html, end_header);
        break;

    case NODE_CODE_BLOCK:
        strbuf_puts(html, "</code></pre>\n");
        break;

    case NODE_INLINE_CODE:
        strbuf_puts(html, "</code>");
        break;

    case NODE_LINK:
        strbuf_puts(html, "</a>");
        break;

    case NODE_STRONG:
        strbuf_puts(html, "</strong>");
        break;

    case NODE_EMPH:
        strbuf_puts(html, "</em>");
        break;

    default:
        break;
    }

    return tight;
}

char *cmark_render_html(cmark_node *root)
{
    char *result;
    strbuf html = GH_BUF_INIT;
    node_to_html(&html, root);
    result = (char *)strbuf_detach(&html);
    strbuf_free(&html);
    return result;
}