src/blocks.c



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

#include "config.h"
#include "parser.h"
#include "cmark.h"
#include "node.h"
#include "references.h"
#include "utf8.h"
#include "scanners.h"
#include "inlines.h"
#include "houdini.h"
#include "buffer.h"
#include "debug.h"

#define CODE_INDENT 4
#define peek_at(i, n) (i)->data[n]

static void
S_parser_feed(cmark_parser *parser, const unsigned char *buffer, size_t len,
          bool eof);

static void
S_process_line(cmark_parser *parser, const unsigned char *buffer,
           size_t bytes);

static cmark_node* make_block(cmark_node_type tag, int start_line, int start_column)
{
    cmark_node* e;

    e = (cmark_node *)calloc(1, sizeof(*e));
    if(e != NULL) {
        e->type = tag;
        e->open = true;
        e->start_line = start_line;
        e->start_column = start_column;
        e->end_line = start_line;
        strbuf_init(&e->string_content, 32);
    }

    return e;
}

// Create a root document cmark_node.
static cmark_node* make_document()
{
    cmark_node *e = make_block(NODE_DOCUMENT, 1, 1);
    return e;
}

cmark_parser *cmark_parser_new()
{
    cmark_parser *parser = (cmark_parser*)malloc(sizeof(cmark_parser));
    cmark_node *document = make_document();
    strbuf *line = (strbuf*)malloc(sizeof(strbuf));
    strbuf *buf  = (strbuf*)malloc(sizeof(strbuf));
    strbuf_init(line, 256);
    strbuf_init(buf, 0);

    parser->refmap = cmark_reference_map_new();
    parser->root = document;
    parser->current = document;
    parser->line_number = 0;
    parser->curline = line;
    parser->linebuf = buf;

    return parser;
}

void cmark_parser_free(cmark_parser *parser)
{
    strbuf_free(parser->curline);
    free(parser->curline);
    strbuf_free(parser->linebuf);
    free(parser->linebuf);
    cmark_reference_map_free(parser->refmap);
    free(parser);
}

static cmark_node*
finalize(cmark_parser *parser, cmark_node* b, int line_number);

// Returns true if line has only space characters, else false.
static bool is_blank(strbuf *s, int offset)
{
    while (offset < s->size) {
        switch (s->ptr[offset]) {
            case '\n':
                return true;
            case ' ':
                offset++;
                break;
            default:
                return false;
        }
    }

    return true;
}

static inline bool can_contain(cmark_node_type parent_type, cmark_node_type child_type)
{
    return ( parent_type == NODE_DOCUMENT ||
            parent_type == NODE_BLOCK_QUOTE ||
            parent_type == NODE_LIST_ITEM ||
            (parent_type == NODE_LIST && child_type == NODE_LIST_ITEM) );
}

static inline bool accepts_lines(cmark_node_type block_type)
{
    return (block_type == NODE_PARAGRAPH ||
        block_type == NODE_HEADER ||
        block_type == NODE_CODE_BLOCK);
}

static void add_line(cmark_node* cmark_node, chunk *ch, int offset)
{
    assert(cmark_node->open);
    strbuf_put(&cmark_node->string_content, ch->data + offset, ch->len - offset);
}

static void remove_trailing_blank_lines(strbuf *ln)
{
    int i;

    for (i = ln->size - 1; i >= 0; --i) {
        unsigned char c = ln->ptr[i];

        if (c != ' ' && c != '\t' && c != '\r' && c != '\n')
            break;
    }

    if (i < 0) {
        strbuf_clear(ln);
        return;
    }

    i = strbuf_strchr(ln, '\n', i);
    if (i >= 0)
        strbuf_truncate(ln, i);
}

// Check to see if a cmark_node ends with a blank line, descending
// if needed into lists and sublists.
static bool ends_with_blank_line(cmark_node* cmark_node)
{
    if (cmark_node->last_line_blank) {
        return true;
    }
    if ((cmark_node->type == NODE_LIST || cmark_node->type == NODE_LIST_ITEM) && cmark_node->last_child) {
        return ends_with_blank_line(cmark_node->last_child);
    } else {
        return false;
    }
}

// Break out of all containing lists
static int break_out_of_lists(cmark_parser *parser, cmark_node ** bptr, int line_number)
{
    cmark_node *container = *bptr;
    cmark_node *b = parser->root;
    // find first containing NODE_LIST:
    while (b && b->type != NODE_LIST) {
        b = b->last_child;
    }
    if (b) {
        while (container && container != b) {
            container = finalize(parser, container, line_number);
        }
        finalize(parser, b, line_number);
        *bptr = b->parent;
    }
    return 0;
}


static cmark_node*
finalize(cmark_parser *parser, cmark_node* b, int line_number)
{
    int firstlinelen;
    int pos;
    cmark_node* item;
    cmark_node* subitem;
    cmark_node* parent;

    parent = b->parent;

    // don't do anything if the cmark_node is already closed
    if (!b->open)
        return parent;

    b->open = false;
    if (line_number > b->start_line) {
        b->end_line = line_number - 1;
    } else {
        b->end_line = line_number;
    }

    switch (b->type) {
        case NODE_PARAGRAPH:
            while (strbuf_at(&b->string_content, 0) == '[' &&
                    (pos = cmark_parse_reference_inline(&b->string_content, parser->refmap))) {

                strbuf_drop(&b->string_content, pos);
            }
            if (is_blank(&b->string_content, 0)) {
                // remove blank node (former reference def)
                cmark_node_free(b);
            }
            break;

        case NODE_CODE_BLOCK:
            if (!b->as.code.fenced) { // indented code
                remove_trailing_blank_lines(&b->string_content);
                strbuf_putc(&b->string_content, '\n');
            } else {

                // first line of contents becomes info
                firstlinelen = strbuf_strchr(&b->string_content, '\n', 0);

                houdini_unescape_html_f(
                        &b->as.code.info,
                        b->string_content.ptr,
                        firstlinelen
                        );

                strbuf_drop(&b->string_content, firstlinelen + 1);

                strbuf_trim(&b->as.code.info);
                strbuf_unescape(&b->as.code.info);
            }
            b->as.literal = chunk_buf_detach(&b->string_content);
            break;

            case NODE_HTML:
            b->as.literal = chunk_buf_detach(&b->string_content);
            break;

        case NODE_LIST: // determine tight/loose status
            b->as.list.tight = true; // tight by default
            item = b->first_child;

            while (item) {
                // check for non-final non-empty list item ending with blank line:
                if (item->last_line_blank && item->next) {
                    b->as.list.tight = false;
                    break;
                }
                // recurse into children of list item, to see if there are
                // spaces between them:
                subitem = item->first_child;
                while (subitem) {
                    if (ends_with_blank_line(subitem) &&
                            (item->next || subitem->next)) {
                        b->as.list.tight = false;
                        break;
                    }
                    subitem = subitem->next;
                }
                if (!(b->as.list.tight)) {
                    break;
                }
                item = item->next;
            }

            break;

        default:
            break;
    }
    return parent;
}

// Add a cmark_node as child of another.  Return pointer to child.
static cmark_node* add_child(cmark_parser *parser, cmark_node* parent,
        cmark_node_type block_type, int start_line, int start_column)
{
    assert(parent);

    // if 'parent' isn't the kind of cmark_node that can accept this child,
    // then back up til we hit a cmark_node that can.
    while (!can_contain(parent->type, block_type)) {
        parent = finalize(parser, parent, start_line);
    }

    cmark_node* child = make_block(block_type, start_line, start_column);
    child->parent = parent;

    if (parent->last_child) {
        parent->last_child->next = child;
        child->prev = parent->last_child;
    } else {
        parent->first_child = child;
        child->prev = NULL;
    }
    parent->last_child = child;
    return child;
}


typedef struct BlockStack {
    struct BlockStack *previous;
    cmark_node *next_sibling;
} block_stack;

// Walk through cmark_node and all children, recursively, parsing
// string content into inline content where appropriate.
static void process_inlines(cmark_node* cur, cmark_reference_map *refmap)
{
    block_stack* stack = NULL;
    block_stack* newstack = NULL;

    while (cur != NULL) {
        switch (cur->type) {
            case NODE_PARAGRAPH:
            case NODE_HEADER:
                cmark_parse_inlines(cur, refmap);
                break;

            default:
                break;
        }

        if (cur->first_child) {
            newstack = (block_stack*)malloc(sizeof(block_stack));
            if (newstack == NULL) break;
            newstack->previous = stack;
            stack = newstack;
            stack->next_sibling = cur->next;
            cur = cur->first_child;
        } else {
            cur = cur->next;
        }

        while (cur == NULL && stack != NULL) {
            cur = stack->next_sibling;
            newstack = stack->previous;
            free(stack);
            stack = newstack;
        }
    }
    while (stack != NULL) {
        newstack = stack->previous;
        free(stack);
        stack = newstack;
    }
}

// Attempts to parse a list item marker (bullet or enumerated).
// On success, returns length of the marker, and populates
// data with the details.  On failure, returns 0.
static int parse_list_marker(chunk *input, int pos, cmark_list **dataptr)
{
    unsigned char c;
    int startpos;
    cmark_list *data;

    startpos = pos;
    c = peek_at(input, pos);

    if ((c == '*' || c == '-' || c == '+') && !scan_hrule(input, pos)) {
        pos++;
        if (!isspace(peek_at(input, pos))) {
            return 0;
        }
        data = (cmark_list *)calloc(1, sizeof(*data));
        if(data == NULL) {
            return 0;
        } else {
            data->marker_offset = 0; // will be adjusted later
            data->list_type = CMARK_BULLET_LIST;
            data->bullet_char = c;
            data->start = 1;
            data->delimiter = CMARK_PERIOD_DELIM;
            data->tight = false;
        }
    } else if (isdigit(c)) {
        int start = 0;

        do {
            start = (10 * start) + (peek_at(input, pos) - '0');
            pos++;
        } while (isdigit(peek_at(input, pos)));

        c = peek_at(input, pos);
        if (c == '.' || c == ')') {
            pos++;
            if (!isspace(peek_at(input, pos))) {
                return 0;
            }
            data = (cmark_list *)calloc(1, sizeof(*data));
            if(data == NULL) {
                return 0;
            } else {
                data->marker_offset = 0; // will be adjusted later
                data->list_type = CMARK_ORDERED_LIST;
                data->bullet_char = 0;
                data->start = start;
                data->delimiter = (c == '.' ? CMARK_PERIOD_DELIM : CMARK_PAREN_DELIM);
                data->tight = false;
            }
        } else {
            return 0;
        }

    } else {
        return 0;
    }

    *dataptr = data;
    return (pos - startpos);
}

// Return 1 if list item belongs in list, else 0.
static int lists_match(cmark_list *list_data, cmark_list *item_data)
{
    return (list_data->list_type == item_data->list_type &&
            list_data->delimiter == item_data->delimiter &&
            // list_data->marker_offset == item_data.marker_offset &&
            list_data->bullet_char == item_data->bullet_char);
}

static cmark_node *finalize_document(cmark_parser *parser)
{
    while (parser->current != parser->root) {
        parser->current = finalize(parser, parser->current,
                       parser->line_number);
    }

    finalize(parser, parser->root, parser->line_number);
    process_inlines(parser->root, parser->refmap);

    return parser->root;
}

cmark_node *cmark_parse_file(FILE *f)
{
    unsigned char buffer[4096];
    cmark_parser *parser = cmark_parser_new();
    size_t bytes;
    cmark_node *document;

    while ((bytes = fread(buffer, 1, sizeof(buffer), f)) > 0) {
        bool eof = bytes < sizeof(buffer);
        S_parser_feed(parser, buffer, bytes, eof);
        if (eof) {
            break;
        }
    }

    document = cmark_parser_finish(parser);
    cmark_parser_free(parser);
    return document;
}

cmark_node *cmark_parse_document(const char *buffer, size_t len)
{
    cmark_parser *parser = cmark_parser_new();
    cmark_node *document;

    S_parser_feed(parser, (const unsigned char *)buffer, len, true);

    document = cmark_parser_finish(parser);
    cmark_parser_free(parser);
    return document;
}

void
cmark_parser_feed(cmark_parser *parser, const char *buffer, size_t len)
{
    S_parser_feed(parser, (const unsigned char *)buffer, len, false);
}

static void
S_parser_feed(cmark_parser *parser, const unsigned char *buffer, size_t len,
          bool eof)
{
    const unsigned char *end = buffer + len;

    while (buffer < end) {
        const unsigned char *eol
            = (const unsigned char *)memchr(buffer, '\n',
                            end - buffer);
        size_t line_len;

        if (eol) {
            line_len = eol + 1 - buffer;
        }
        else if (eof) {
            line_len = end - buffer;
        }
        else {
            strbuf_put(parser->linebuf, buffer, end - buffer);
            break;
        }

        if (parser->linebuf->size > 0) {
            strbuf_put(parser->linebuf, buffer, line_len);
            S_process_line(parser, parser->linebuf->ptr,
                       parser->linebuf->size);
            strbuf_clear(parser->linebuf);
        }
        else {
            S_process_line(parser, buffer, line_len);
        }

        buffer += line_len;
    }
}

static void chop_trailing_hashtags(chunk *ch)
{
    int n, orig_n;

    chunk_rtrim(ch);
    orig_n = n = ch->len - 1;

    // if string ends in space followed by #s, remove these:
    while (n >= 0 && peek_at(ch, n) == '#')
        n--;

    // Check for a be a space before the final #s:
    if (n != orig_n && n >= 0 && peek_at(ch, n) == ' ') {
        ch->len = n;
        chunk_rtrim(ch);
    }
}

static void
S_process_line(cmark_parser *parser, const unsigned char *buffer, size_t bytes)
{
    cmark_node* last_matched_container;
    int offset = 0;
    int matched = 0;
    int lev = 0;
    int i;
    cmark_list *data = NULL;
    bool all_matched = true;
    cmark_node* container;
    cmark_node* cur = parser->current;
    bool blank = false;
    int first_nonspace;
    int indent;
    chunk input;

    utf8proc_detab(parser->curline, buffer, bytes);

    // Add a newline to the end if not present:
    // TODO this breaks abstraction:
    if (parser->curline->ptr[parser->curline->size - 1] != '\n') {
        strbuf_putc(parser->curline, '\n');
    }
    input.data = parser->curline->ptr;
    input.len = parser->curline->size;

    // container starts at the document root.
    container = parser->root;

    parser->line_number++;

    // for each containing cmark_node, try to parse the associated line start.
    // bail out on failure:  container will point to the last matching cmark_node.

    while (container->last_child && container->last_child->open) {
        container = container->last_child;

        first_nonspace = offset;
        while (peek_at(&input, first_nonspace) == ' ') {
            first_nonspace++;
        }

        indent = first_nonspace - offset;
        blank = peek_at(&input, first_nonspace) == '\n';

        if (container->type == NODE_BLOCK_QUOTE) {
            matched = indent <= 3 && peek_at(&input, first_nonspace) == '>';
            if (matched) {
                offset = first_nonspace + 1;
                if (peek_at(&input, offset) == ' ')
                    offset++;
            } else {
                all_matched = false;
            }

        } else if (container->type == NODE_LIST_ITEM) {

            if (indent >= container->as.list.marker_offset +
                    container->as.list.padding) {
                offset += container->as.list.marker_offset +
                    container->as.list.padding;
            } else if (blank) {
                offset = first_nonspace;
            } else {
                all_matched = false;
            }

        } else if (container->type == NODE_CODE_BLOCK) {

            if (!container->as.code.fenced) { // indented
                if (indent >= CODE_INDENT) {
                    offset += CODE_INDENT;
                } else if (blank) {
                    offset = first_nonspace;
                } else {
                    all_matched = false;
                }
            } else {
                // skip optional spaces of fence offset
                i = container->as.code.fence_offset;
                while (i > 0 && peek_at(&input, offset) == ' ') {
                    offset++;
                    i--;
                }
            }

        } else if (container->type == NODE_HEADER) {

            // a header can never contain more than one line
            all_matched = false;
            if (blank) {
                container->last_line_blank = true;
            }

        } else if (container->type == NODE_HTML) {

            if (blank) {
                container->last_line_blank = true;
                all_matched = false;
            }

        } else if (container->type == NODE_PARAGRAPH) {

            if (blank) {
                container->last_line_blank = true;
                all_matched = false;
            }

        }

        if (!all_matched) {
            container = container->parent;  // back up to last matching cmark_node
            break;
        }
    }

    last_matched_container = container;

    // check to see if we've hit 2nd blank line, break out of list:
    if (blank && container->last_line_blank) {
        break_out_of_lists(parser, &container, parser->line_number);
    }

    // unless last matched container is code cmark_node, try new container starts:
    while (container->type != NODE_CODE_BLOCK &&
            container->type != NODE_HTML) {

        first_nonspace = offset;
        while (peek_at(&input, first_nonspace) == ' ')
            first_nonspace++;

        indent = first_nonspace - offset;
        blank = peek_at(&input, first_nonspace) == '\n';

        if (indent >= CODE_INDENT) {
            if (cur->type != NODE_PARAGRAPH && !blank) {
                offset += CODE_INDENT;
                container = add_child(parser, container, NODE_CODE_BLOCK, parser->line_number, offset + 1);
                container->as.code.fenced = false;
                container->as.code.fence_char = 0;
                container->as.code.fence_length = 0;
                container->as.code.fence_offset = 0;
                strbuf_init(&container->as.code.info, 0);
            } else { // indent > 4 in lazy line
                break;
            }

        } else if (peek_at(&input, first_nonspace) == '>') {

            offset = first_nonspace + 1;
            // optional following character
            if (peek_at(&input, offset) == ' ')
                offset++;
            container = add_child(parser, container, NODE_BLOCK_QUOTE, parser->line_number, offset + 1);

        } else if ((matched = scan_atx_header_start(&input, first_nonspace))) {

            offset = first_nonspace + matched;
            container = add_child(parser, container, NODE_HEADER, parser->line_number, offset + 1);

            int hashpos = chunk_strchr(&input, '#', first_nonspace);
            int level = 0;

            while (peek_at(&input, hashpos) == '#') {
                level++;
                hashpos++;
            }
            container->as.header.level = level;
            container->as.header.setext = false;

        } else if ((matched = scan_open_code_fence(&input, first_nonspace))) {

            container = add_child(parser, container, NODE_CODE_BLOCK, parser->line_number, first_nonspace + 1);
            container->as.code.fenced = true;
            container->as.code.fence_char = peek_at(&input, first_nonspace);
            container->as.code.fence_length = matched;
            container->as.code.fence_offset = first_nonspace - offset;
            strbuf_init(&container->as.code.info, 0);
            offset = first_nonspace + matched;

        } else if ((matched = scan_html_block_tag(&input, first_nonspace))) {

            container = add_child(parser, container, NODE_HTML, parser->line_number, first_nonspace + 1);
            // note, we don't adjust offset because the tag is part of the text

        } else if (container->type == NODE_PARAGRAPH &&
                (lev = scan_setext_header_line(&input, first_nonspace)) &&
                // check that there is only one line in the paragraph:
                strbuf_strrchr(&container->string_content, '\n',
                    strbuf_len(&container->string_content) - 2) < 0) {

            container->type = NODE_HEADER;
            container->as.header.level = lev;
            container->as.header.setext = true;
            offset = input.len - 1;

        } else if (!(container->type == NODE_PARAGRAPH && !all_matched) &&
                (matched = scan_hrule(&input, first_nonspace))) {

            // it's only now that we know the line is not part of a setext header:
            container = add_child(parser, container, NODE_HRULE, parser->line_number, first_nonspace + 1);
            container = finalize(parser, container,
                         parser->line_number);
            offset = input.len - 1;

        } else if ((matched = parse_list_marker(&input, first_nonspace, &data))) {

            // compute padding:
            offset = first_nonspace + matched;
            i = 0;
            while (i <= 5 && peek_at(&input, offset + i) == ' ') {
                i++;
            }
            // i = number of spaces after marker, up to 5
            if (i >= 5 || i < 1 || peek_at(&input, offset) == '\n') {
                data->padding = matched + 1;
                if (i > 0) {
                    offset += 1;
                }
            } else {
                data->padding = matched + i;
                offset += i;
            }

            // check container; if it's a list, see if this list item
            // can continue the list; otherwise, create a list container.

            data->marker_offset = indent;

            if (container->type != NODE_LIST ||
                    !lists_match(&container->as.list, data)) {
                container = add_child(parser, container, NODE_LIST, parser->line_number,
                        first_nonspace + 1);

                memcpy(&container->as.list, data, sizeof(*data));
            }

            // add the list item
            container = add_child(parser, container, NODE_LIST_ITEM, parser->line_number,
                    first_nonspace + 1);
            /* TODO: static */
            memcpy(&container->as.list, data, sizeof(*data));
            free(data);
        } else {
            break;
        }

        if (accepts_lines(container->type)) {
            // if it's a line container, it can't contain other containers
            break;
        }
    }

    // what remains at offset is a text line.  add the text to the
    // appropriate container.

    first_nonspace = offset;
    while (peek_at(&input, first_nonspace) == ' ')
        first_nonspace++;

    indent = first_nonspace - offset;
    blank = peek_at(&input, first_nonspace) == '\n';

    // cmark_node quote lines are never blank as they start with >
    // and we don't count blanks in fenced code for purposes of tight/loose
    // lists or breaking out of lists.  we also don't set last_line_blank
    // on an empty list item.
    container->last_line_blank = (blank &&
            container->type != NODE_BLOCK_QUOTE &&
            container->type != NODE_HEADER &&
            !(container->type == NODE_CODE_BLOCK &&
                container->as.code.fenced) &&
            !(container->type == NODE_LIST_ITEM &&
                container->first_child == NULL &&
                container->start_line == parser->line_number));

    cmark_node *cont = container;
    while (cont->parent) {
        cont->parent->last_line_blank = false;
        cont = cont->parent;
    }

    if (cur != last_matched_container &&
            container == last_matched_container &&
            !blank &&
            cur->type == NODE_PARAGRAPH &&
            strbuf_len(&cur->string_content) > 0) {

        add_line(cur, &input, offset);

    } else { // not a lazy continuation

        // finalize any blocks that were not matched and set cur to container:
        while (cur != last_matched_container) {
            cur = finalize(parser, cur, parser->line_number);
            assert(cur != NULL);
        }

        if (container->type == NODE_CODE_BLOCK &&
            !container->as.code.fenced) {

            add_line(container, &input, offset);

        } else if (container->type == NODE_CODE_BLOCK &&
               container->as.code.fenced) {
            matched = 0;

            if (indent <= 3 &&
                    peek_at(&input, first_nonspace) == container->as.code.fence_char) {
                int fence_len = scan_close_code_fence(&input, first_nonspace);
                if (fence_len > container->as.code.fence_length)
                    matched = 1;
            }

            if (matched) {
                // if closing fence, don't add line to container; instead, close it:
                container = finalize(parser, container,
                             parser->line_number);
            } else {
                add_line(container, &input, offset);
            }

        } else if (container->type == NODE_HTML) {

            add_line(container, &input, offset);

        } else if (blank) {

            // ??? do nothing

        } else if (container->type == NODE_HEADER) {

            chop_trailing_hashtags(&input);
            add_line(container, &input, first_nonspace);
            container = finalize(parser, container,
                         parser->line_number);

        } else if (accepts_lines(container->type)) {

            add_line(container, &input, first_nonspace);

        } else if (container->type != NODE_HRULE &&
               container->type != NODE_HEADER) {

            // create paragraph container for line
            container = add_child(parser, container, NODE_PARAGRAPH, parser->line_number, first_nonspace + 1);
            add_line(container, &input, first_nonspace);

        } else {
            assert(false);
        }

        parser->current = container;
    }
    strbuf_clear(parser->curline);

}

cmark_node *cmark_parser_finish(cmark_parser *parser)
{
    if (parser->linebuf->size) {
        S_process_line(parser, parser->linebuf->ptr,
                 parser->linebuf->size);
        strbuf_clear(parser->linebuf);
    }

    finalize_document(parser);
    strbuf_free(parser->curline);
#if CMARK_DEBUG_NODES
    if (cmark_node_check(parser->root, stderr)) {
        abort();
    }
#endif
    return parser->root;
}