From eef794b8c645ea08fae3a9818c3a45ac5a4bccb4 Mon Sep 17 00:00:00 2001
From: AnotherTest <ali.mpfard@gmail.com>
Date: Sun, 20 Sep 2020 20:42:23 +0430
Subject: [PATCH] LibMarkdown: Parse paragraphs line-wise

This gets rid of the doubled-up checks in `Paragraph::parse()`, and
makes a paragraph the last possible kind of block to be parsed.
---
 Libraries/LibMarkdown/Document.cpp  | 26 +++++++++++--
 Libraries/LibMarkdown/Paragraph.cpp | 60 ++++++++---------------------
 Libraries/LibMarkdown/Paragraph.h   | 25 ++++++++++--
 3 files changed, 61 insertions(+), 50 deletions(-)

diff --git a/Libraries/LibMarkdown/Document.cpp b/Libraries/LibMarkdown/Document.cpp
index ba3d244b74..3e036dab16 100644
--- a/Libraries/LibMarkdown/Document.cpp
+++ b/Libraries/LibMarkdown/Document.cpp
@@ -81,6 +81,7 @@ OwnPtr<Document> Document::parse(const StringView& str)
     auto lines = lines_vec.begin();
     auto document = make<Document>();
     auto& blocks = document->m_blocks;
+    NonnullOwnPtrVector<Paragraph::Line> paragraph_lines;
 
     while (true) {
         if (lines.is_end())
@@ -91,11 +92,30 @@ OwnPtr<Document> Document::parse(const StringView& str)
             continue;
         }
 
-        bool any = helper<Table>(lines, blocks) || 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<CodeBlock>(lines, blocks)
+            || helper<Heading>(lines, blocks);
 
-        if (!any)
+        if (any) {
+            if (!paragraph_lines.is_empty()) {
+                auto last_block = document->m_blocks.take_last();
+                auto paragraph = make<Paragraph>(move(paragraph_lines));
+                document->m_blocks.append(move(paragraph));
+                document->m_blocks.append(move(last_block));
+                paragraph_lines.clear();
+            }
+            continue;
+        }
+
+        auto line = Paragraph::Line::parse(lines);
+        if (!line)
             return nullptr;
+
+        paragraph_lines.append(line.release_nonnull());
+    }
+
+    if (!paragraph_lines.is_empty()) {
+        auto paragraph = make<Paragraph>(move(paragraph_lines));
+        document->m_blocks.append(move(paragraph));
     }
 
     return document;
diff --git a/Libraries/LibMarkdown/Paragraph.cpp b/Libraries/LibMarkdown/Paragraph.cpp
index f44da06fbb..0e2b7f9df4 100644
--- a/Libraries/LibMarkdown/Paragraph.cpp
+++ b/Libraries/LibMarkdown/Paragraph.cpp
@@ -33,7 +33,13 @@ String Paragraph::render_to_html() const
 {
     StringBuilder builder;
     builder.appendf("<p>");
-    builder.append(m_text.render_to_html());
+    bool first = true;
+    for (auto& line : m_lines) {
+        if (!first)
+            builder.append(' ');
+        first = false;
+        builder.append(line.text().render_to_html());
+    }
     builder.appendf("</p>\n");
     return builder.build();
 }
@@ -41,58 +47,26 @@ String Paragraph::render_to_html() const
 String Paragraph::render_for_terminal(size_t) const
 {
     StringBuilder builder;
-    builder.append(m_text.render_for_terminal());
+    bool first = true;
+    for (auto& line : m_lines) {
+        if (!first)
+            builder.append(' ');
+        first = false;
+        builder.append(line.text().render_for_terminal());
+    }
     builder.appendf("\n\n");
     return builder.build();
 }
 
-OwnPtr<Paragraph> Paragraph::parse(Vector<StringView>::ConstIterator& lines)
+OwnPtr<Paragraph::Line> Paragraph::Line::parse(Vector<StringView>::ConstIterator& lines)
 {
     if (lines.is_end())
         return nullptr;
 
-    bool first = true;
-    StringBuilder builder;
-
-    while (true) {
-        if (lines.is_end())
-            break;
-        StringView line = *lines;
-        if (line.is_empty())
-            break;
-        char ch = line[0];
-        // See if it looks like a blockquote
-        // or like an indented block.
-        if (ch == '>' || ch == ' ')
-            break;
-        if (line.length() > 1) {
-            // See if it looks like a heading.
-            if (ch == '#' && (line[1] == '#' || line[1] == ' '))
-                break;
-            // See if it looks like a code block.
-            if (ch == '`' && line[1] == '`')
-                break;
-            // See if it looks like a list.
-            if (ch == '*' || ch == '-')
-                if (line[1] == ' ')
-                    break;
-        }
-
-        if (!first)
-            builder.append(' ');
-        builder.append(line);
-        first = false;
-        ++lines;
-    }
-
-    if (first)
-        return nullptr;
-
-    auto text = Text::parse(builder.build());
+    auto text = Text::parse(*lines++);
     if (!text.has_value())
         return nullptr;
 
-    return make<Paragraph>(move(text.value()));
+    return make<Paragraph::Line>(text.release_value());
 }
-
 }
diff --git a/Libraries/LibMarkdown/Paragraph.h b/Libraries/LibMarkdown/Paragraph.h
index d5e63a03c2..98e9dc9b9e 100644
--- a/Libraries/LibMarkdown/Paragraph.h
+++ b/Libraries/LibMarkdown/Paragraph.h
@@ -26,6 +26,7 @@
 
 #pragma once
 
+#include <AK/NonnullOwnPtrVector.h>
 #include <AK/OwnPtr.h>
 #include <LibMarkdown/Block.h>
 #include <LibMarkdown/Text.h>
@@ -34,18 +35,34 @@ namespace Markdown {
 
 class Paragraph final : public Block {
 public:
-    explicit Paragraph(Text&& text)
-        : m_text(move(text))
+    class Line {
+    public:
+        explicit Line(Text&& text)
+            : m_text(move(text))
+        {
+        }
+
+        static OwnPtr<Line> parse(Vector<StringView>::ConstIterator& lines);
+        const Text& text() const { return m_text; }
+
+    private:
+        Text m_text;
+    };
+
+    Paragraph(NonnullOwnPtrVector<Line>&& lines)
+        : m_lines(move(lines))
     {
     }
+
     virtual ~Paragraph() override { }
 
     virtual String render_to_html() const override;
     virtual String render_for_terminal(size_t view_width = 0) const override;
-    static OwnPtr<Paragraph> parse(Vector<StringView>::ConstIterator& lines);
+
+    void add_line(NonnullOwnPtr<Line>&& line);
 
 private:
-    Text m_text;
+    NonnullOwnPtrVector<Line> m_lines;
 };
 
 }