LibMarkdown: Add support for Tables

This adds support for GFM-like tables.
The HTML rendering ignores the alignments and relative sizes, but the
terminal view does not!

Libraries/LibMarkdown/CMakeLists.txt

@@ -4,6 +4,7 @@ set(SOURCES
     Heading.cpp
     List.cpp
     Paragraph.cpp
+    Table.cpp
     Text.cpp
 )
 

Libraries/LibMarkdown/Document.cpp

@@ -30,6 +30,7 @@
 #include <LibMarkdown/Heading.h>
 #include <LibMarkdown/List.h>
 #include <LibMarkdown/Paragraph.h>
+#include <LibMarkdown/Table.h>
 
 namespace Markdown {
 
@@ -90,7 +91,8 @@ OwnPtr<Document> Document::parse(const StringView& str)
             continue;
         }
 
-        bool any = helper<List>(lines, blocks) || helper<Paragraph>(lines, blocks) || helper<CodeBlock>(lines, blocks) || helper<Heading>(lines, blocks);
+        bool any = helper<Table>(lines, blocks) || helper<List>(lines, blocks) || helper<Paragraph>(lines, blocks)
+            || helper<CodeBlock>(lines, blocks) || helper<Heading>(lines, blocks);
 
         if (!any)
             return nullptr;

Libraries/LibMarkdown/Table.cpp

@@ -0,0 +1,241 @@
+/*
+ * Copyright (c) 2020, the SerenityOS developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <AK/StringBuilder.h>
+#include <LibMarkdown/Table.h>
+
+namespace Markdown {
+
+String Table::render_for_terminal(size_t view_width) const
+{
+    auto unit_width_length = view_width == 0 ? 4 : ((float)(view_width - m_columns.size()) / (float)m_total_width);
+    StringBuilder format_builder;
+    StringBuilder builder;
+
+    auto write_aligned = [&](const auto& text, auto width, auto alignment) {
+        size_t original_length = 0;
+        for (auto& span : text.spans())
+            original_length += span.text.length();
+        auto string = text.render_for_terminal();
+        format_builder.clear();
+        if (alignment == Alignment::Center) {
+            auto padding_length = (width - original_length) / 2;
+            builder.appendf("%*s%s%*s", padding_length, "", string.characters(), padding_length, "");
+            if ((width - original_length) % 2)
+                builder.append(' ');
+        } else {
+            format_builder.appendf("%%%s%zus", alignment == Alignment::Left ? "-" : "", width + (string.length() - original_length));
+            builder.appendf(
+                format_builder.to_string().characters(),
+                string.characters());
+        }
+    };
+
+    bool first = true;
+    for (auto& col : m_columns) {
+        if (!first)
+            builder.append('|');
+        first = false;
+        size_t width = col.relative_width * unit_width_length;
+        write_aligned(col.header, width, col.alignment);
+    }
+
+    builder.append("\n");
+    for (size_t i = 0; i < view_width; ++i)
+        builder.append('-');
+    builder.append("\n");
+
+    for (size_t i = 0; i < m_row_count; ++i) {
+        bool first = true;
+        for (auto& col : m_columns) {
+            ASSERT(i < col.rows.size());
+            auto& cell = col.rows[i];
+
+            if (!first)
+                builder.append('|');
+            first = false;
+
+            size_t width = col.relative_width * unit_width_length;
+            write_aligned(cell, width, col.alignment);
+        }
+        builder.append("\n");
+    }
+
+    return builder.to_string();
+}
+
+String Table::render_to_html() const
+{
+    StringBuilder builder;
+
+    builder.append("<table>");
+    builder.append("<thead>");
+    builder.append("<tr>");
+    for (auto& column : m_columns) {
+        builder.append("<th>");
+        builder.append(column.header.render_to_html());
+        builder.append("</th>");
+    }
+    builder.append("</tr>");
+    builder.append("</thead>");
+    builder.append("<tbody>");
+    for (size_t i = 0; i < m_row_count; ++i) {
+        builder.append("<tr>");
+        for (auto& column : m_columns) {
+            ASSERT(i < column.rows.size());
+            builder.append("<td>");
+            builder.append(column.rows[i].render_to_html());
+            builder.append("</td>");
+        }
+        builder.append("</tr>");
+    }
+    builder.append("</tbody>");
+    builder.append("</table>");
+
+    return builder.to_string();
+}
+
+OwnPtr<Table> Table::parse(Vector<StringView>::ConstIterator& lines)
+{
+    auto peek_it = lines;
+    auto first_line = *peek_it;
+    if (!first_line.starts_with('|'))
+        return nullptr;
+
+    ++peek_it;
+
+    if (peek_it.is_end())
+        return nullptr;
+
+    auto header_segments = first_line.split_view('|', true);
+    auto header_delimiters = peek_it->split_view('|', true);
+
+    if (!header_segments.is_empty())
+        header_segments.take_first();
+    if (!header_segments.is_empty() && header_segments.last().is_empty())
+        header_segments.take_last();
+
+    if (!header_delimiters.is_empty())
+        header_delimiters.take_first();
+    if (!header_delimiters.is_empty() && header_delimiters.last().is_empty())
+        header_delimiters.take_last();
+
+    ++peek_it;
+
+    if (header_delimiters.size() != header_segments.size())
+        return nullptr;
+
+    if (header_delimiters.is_empty())
+        return nullptr;
+
+    size_t total_width = 0;
+
+    auto table = make<Table>();
+    table->m_columns.resize(header_delimiters.size());
+
+    for (size_t i = 0; i < header_segments.size(); ++i) {
+        auto text_option = Text::parse(header_segments[i]);
+        if (!text_option.has_value())
+            return nullptr; // An invalid 'text' in the header should just fail the table parse.
+
+        auto text = text_option.release_value();
+        auto& column = table->m_columns[i];
+
+        column.header = move(text);
+
+        auto delimiter = header_delimiters[i].trim_whitespace();
+
+        auto align_left = delimiter.starts_with(':');
+        auto align_right = delimiter != ":" && delimiter.ends_with(':');
+
+        if (align_left)
+            delimiter = delimiter.substring_view(1, delimiter.length() - 1);
+        if (align_right)
+            delimiter = delimiter.substring_view(0, delimiter.length() - 1);
+
+        if (align_left && align_right)
+            column.alignment = Alignment::Center;
+        else if (align_right)
+            column.alignment = Alignment::Right;
+        else
+            column.alignment = Alignment::Left;
+
+        size_t relative_width = delimiter.length();
+        for (auto ch : delimiter) {
+            if (ch != '-') {
+                dbg() << "Invalid character _" << ch << "_ in table heading delimiter (ignored)";
+                --relative_width;
+            }
+        }
+
+        column.relative_width = relative_width;
+        total_width += relative_width;
+    }
+
+    table->m_total_width = total_width;
+
+    for (off_t i = 0; i < peek_it - lines; ++i)
+        ++lines;
+
+    size_t row_count = 0;
+    ++lines;
+    while (!lines.is_end()) {
+        auto& line = *lines;
+        if (!line.starts_with('|'))
+            break;
+
+        ++lines;
+
+        auto segments = line.split_view('|', true);
+        segments.take_first();
+        if (!segments.is_empty() && segments.last().is_empty())
+            segments.take_last();
+        ++row_count;
+
+        for (size_t i = 0; i < header_segments.size(); ++i) {
+            if (i >= segments.size()) {
+                // Ran out of segments, but still have headers.
+                // Just make an empty cell.
+                table->m_columns[i].rows.append(Text { "" });
+            } else {
+                auto text_option = Text::parse(segments[i]);
+                // We treat an invalid 'text' as a literal.
+                if (text_option.has_value()) {
+                    auto text = text_option.release_value();
+                    table->m_columns[i].rows.append(move(text));
+                } else {
+                    table->m_columns[i].rows.append(Text { segments[i] });
+                }
+            }
+        }
+    }
+
+    table->m_row_count = row_count;
+
+    return move(table);
+}
+
+}

Libraries/LibMarkdown/Table.h

@@ -0,0 +1,64 @@
+/*
+ * Copyright (c) 2020, the SerenityOS developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <AK/NonnullOwnPtrVector.h>
+#include <AK/OwnPtr.h>
+#include <LibMarkdown/Block.h>
+#include <LibMarkdown/Text.h>
+
+namespace Markdown {
+
+class Table final : public Block {
+public:
+    enum class Alignment {
+        Center,
+        Left,
+        Right,
+    };
+
+    struct Column {
+        Text header;
+        Vector<Text> rows;
+        Alignment alignment { Alignment::Left };
+        size_t relative_width { 0 };
+    };
+
+    Table() { }
+    virtual ~Table() override { }
+
+    virtual String render_to_html() const override;
+    virtual String render_for_terminal(size_t view_width = 0) const override;
+    static OwnPtr<Table> parse(Vector<StringView>::ConstIterator& lines);
+
+private:
+    Vector<Column> m_columns;
+    size_t m_total_width { 1 };
+    size_t m_row_count { 0 };
+};
+
+}