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1 //===--- Markup.h -------------------------------------------*- C++-*------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // A model of formatted text that can be rendered to plaintext or markdown.
10 //
11 //===----------------------------------------------------------------------===//
12 #ifndef LLVM_CLANG_TOOLS_EXTRA_CLANGD_SUPPORT_MARKUP_H
13 #define LLVM_CLANG_TOOLS_EXTRA_CLANGD_SUPPORT_MARKUP_H
14 
15 #include "llvm/Support/raw_ostream.h"
16 #include <cstddef>
17 #include <memory>
18 #include <string>
19 #include <vector>
20 
21 namespace clang {
22 namespace clangd {
23 namespace markup {
24 
25 /// Holds text and knows how to lay it out. Multiple blocks can be grouped to
26 /// form a document. Blocks include their own trailing newlines, container
27 /// should trim them if need be.
28 class Block {
29 public:
30   virtual void renderMarkdown(llvm::raw_ostream &OS) const = 0;
31   virtual void renderPlainText(llvm::raw_ostream &OS) const = 0;
32   virtual std::unique_ptr<Block> clone() const = 0;
33   std::string asMarkdown() const;
34   std::string asPlainText() const;
35 
isRuler()36   virtual bool isRuler() const { return false; }
37   virtual ~Block() = default;
38 };
39 
40 /// Represents parts of the markup that can contain strings, like inline code,
41 /// code block or plain text.
42 /// One must introduce different paragraphs to create separate blocks.
43 class Paragraph : public Block {
44 public:
45   void renderMarkdown(llvm::raw_ostream &OS) const override;
46   void renderPlainText(llvm::raw_ostream &OS) const override;
47   std::unique_ptr<Block> clone() const override;
48 
49   /// Append plain text to the end of the string.
50   Paragraph &appendText(llvm::StringRef Text);
51 
52   /// Append inline code, this translates to the ` block in markdown.
53   /// \p Preserve indicates the code span must be apparent even in plaintext.
54   Paragraph &appendCode(llvm::StringRef Code, bool Preserve = false);
55 
56   /// Ensure there is space between the surrounding chunks.
57   /// Has no effect at the beginning or end of a paragraph.
58   Paragraph &appendSpace();
59 
60 private:
61   struct Chunk {
62     enum {
63       PlainText,
64       InlineCode,
65     } Kind = PlainText;
66     // Preserve chunk markers in plaintext.
67     bool Preserve = false;
68     std::string Contents;
69     // Whether this chunk should be surrounded by whitespace.
70     // Consecutive SpaceAfter and SpaceBefore will be collapsed into one space.
71     // Code spans don't usually set this: their spaces belong "inside" the span.
72     bool SpaceBefore = false;
73     bool SpaceAfter = false;
74   };
75   std::vector<Chunk> Chunks;
76 };
77 
78 /// Represents a sequence of one or more documents. Knows how to print them in a
79 /// list like format, e.g. by prepending with "- " and indentation.
80 class BulletList : public Block {
81 public:
82   void renderMarkdown(llvm::raw_ostream &OS) const override;
83   void renderPlainText(llvm::raw_ostream &OS) const override;
84   std::unique_ptr<Block> clone() const override;
85 
86   class Document &addItem();
87 
88 private:
89   std::vector<class Document> Items;
90 };
91 
92 /// A format-agnostic representation for structured text. Allows rendering into
93 /// markdown and plaintext.
94 class Document {
95 public:
96   Document() = default;
Document(const Document & Other)97   Document(const Document &Other) { *this = Other; }
98   Document &operator=(const Document &);
99   Document(Document &&) = default;
100   Document &operator=(Document &&) = default;
101 
102   void append(Document Other);
103 
104   /// Adds a semantical block that will be separate from others.
105   Paragraph &addParagraph();
106   /// Inserts a horizontal separator to the document.
107   void addRuler();
108   /// Adds a block of code. This translates to a ``` block in markdown. In plain
109   /// text representation, the code block will be surrounded by newlines.
110   void addCodeBlock(std::string Code, std::string Language = "cpp");
111   /// Heading is a special type of paragraph that will be prepended with \p
112   /// Level many '#'s in markdown.
113   Paragraph &addHeading(size_t Level);
114 
115   BulletList &addBulletList();
116 
117   /// Doesn't contain any trailing newlines.
118   /// We try to make the markdown human-readable, e.g. avoid extra escaping.
119   /// At least one client (coc.nvim) displays the markdown verbatim!
120   std::string asMarkdown() const;
121   /// Doesn't contain any trailing newlines.
122   std::string asPlainText() const;
123 
124 private:
125   std::vector<std::unique_ptr<Block>> Children;
126 };
127 } // namespace markup
128 } // namespace clangd
129 } // namespace clang
130 
131 #endif
132