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What is markdown package

The Package markdown is a simple markdown builder in golang. The markdown package assembles Markdown using method chaining, not uses a template engine like html/template. The syntax of Markdown follows GitHub Markdown.

The markdown package was initially developed to save test results in nao1215/spectest. Therefore, the markdown package implements the features required by spectest. For example, the markdown package supports mermaid sequence diagrams (entity relationship diagram, sequence diagram, flowchart, pie chart), which was a necessary feature in spectest.

Additionally, complex code that increases the complexity of the library, such as generating nested lists, will not be added. I want to keep this library as simple as possible.

Supported OS and go version

OS: Linux, macOS, Windows
Go: 1.20 or later

Supported Markdown features

[x] Heading; H1, H2, H3, H4, H5, H6
[x] Blockquote
[x] Bullet list
[x] Ordered list
[x] Checkbox list
[x] Code blocks
[x] Horizontal rule
[x] Table
[x] Text formatting; bold, italic, code, strikethrough, bold italic
[x] Text with link
[x] Text with image
[x] Plain text
[x] Details
[x] Alerts; NOTE, TIP, IMPORTANT, CAUTION, WARNING
[x] mermaid sequence diagram
[x] mermaid entity relationship diagram
[x] mermaid flowchart
[x] mermaid pie chart

Features not in Markdown syntax

Generate badges; RedBadge(), YellowBadge(), GreenBadge().
Generate an index for a directory full of markdown files; GenerateIndex()

Example

Basic usage

package main

import (
    "os"

    md "github.com/nao1215/markdown"
)

func main() {
    md.NewMarkdown(os.Stdout).
        H1("This is H1").
        PlainText("This is plain text").
        H2f("This is %s with text format", "H2").
        PlainTextf("Text formatting, such as %s and %s, %s styles.",
            md.Bold("bold"), md.Italic("italic"), md.Code("code")).
        H2("Code Block").
        CodeBlocks(md.SyntaxHighlightGo,
            `package main
import "fmt"

func main() {
    fmt.Println("Hello, World!")
}`).
        H2("List").
        BulletList("Bullet Item 1", "Bullet Item 2", "Bullet Item 3").
        OrderedList("Ordered Item 1", "Ordered Item 2", "Ordered Item 3").
        H2("CheckBox").
        CheckBox([]md.CheckBoxSet{
            {Checked: false, Text: md.Code("sample code")},
            {Checked: true, Text: md.Link("Go", "https://golang.org")},
            {Checked: false, Text: md.Strikethrough("strikethrough")},
        }).
        H2("Blockquote").
        Blockquote("If you can dream it, you can do it.").
        H3("Horizontal Rule").
        HorizontalRule().
        H2("Table").
        Table(md.TableSet{
            Header: []string{"Name", "Age", "Country"},
            Rows: [][]string{
                {"David", "23", "USA"},
                {"John", "30", "UK"},
                {"Bob", "25", "Canada"},
            },
        }).
        H2("Image").
        PlainTextf(md.Image("sample_image", "./sample.png")).
        Build()
}

Output:

# This is H1
This is plain text

## This is H2 with text format
Text formatting, such as **bold** and *italic*, `code` styles.

## Code Block
```go
package main
import "fmt"

func main() {
        fmt.Println("Hello, World!")
}

List

Bullet Item 1
Bullet Item 2
Bullet Item 3
1. Ordered Item 1
2. Ordered Item 2
3. Ordered Item 3

CheckBox

[ ] sample code
[x] Go
[ ] ~~strikethrough~~

Blockquote

If you can dream it, you can do it.

Horizontal Rule

Table

NAME	AGE	COUNTRY
David	23	USA
John	30	UK
Bob	25	Canada

Image

sample_image


If you want to see how it looks in Markdown, please refer to the following link.
- [sample.md](./doc/generated_example.md)

### Generate Markdown using `"go generate ./..."`
You can generate Markdown using `go generate`. Please define code to generate Markdown first. Then, run `"go generate ./..."` to generate Markdown.

[Code example:](./doc/generate/main.go)
```go
package main

import (
    "os"

    md "github.com/nao1215/markdown"
)

//go:generate go run main.go

func main() {
    f, err := os.Create("generated.md")
    if err != nil {
        panic(err)
    }
    defer f.Close()

    md.NewMarkdown(f).
        H1("go generate example").
        PlainText("This markdown is generated by `go generate`").
        Build()
}

Run below command:

go generate ./...

Output:

# go generate example
This markdown is generated by `go generate`

Alerts syntax

The markdown package can create alerts. Alerts are useful for displaying important information in Markdown. This syntax is supported by GitHub. Code example:

    md.NewMarkdown(f).
        H1("Alert example").
        Note("This is note").LF().
        Tip("This is tip").LF().
        Important("This is important").LF().
        Warning("This is warning").LF().
        Caution("This is caution").LF().
        Build()

Output:

# Alert example
> [!NOTE]  
> This is note

> [!TIP]  
> This is tip

> [!IMPORTANT]  
> This is important

> [!WARNING]  
> This is warning

> [!CAUTION]  
> This is caution

Your alert will look like this;

[!NOTE]
This is note

[!TIP]
This is tip

[!IMPORTANT]
This is important

[!WARNING]
This is warning

[!CAUTION]
This is caution

Status badge syntax

The markdown package can create red, yellow, and green status badges. Code example:

    md.NewMarkdown(os.Stdout).
        H1("badge example").
        RedBadge("red_badge").
        YellowBadge("yellow_badge").
        GreenBadge("green_badge").
        BlueBadge("blue_badge").
        Build()

Output:

# badge example
![Badge](https://img.shields.io/badge/red_badge-red)
![Badge](https://img.shields.io/badge/yellow_badge-yellow)
![Badge](https://img.shields.io/badge/green_badge-green)
![Badge](https://img.shields.io/badge/blue_badge-blue)

Your badge will look like this;

Mermaid sequence diagram syntax

package main

import (
    "os"

    "github.com/nao1215/markdown"
    "github.com/nao1215/mermaid/sequence"
)

//go:generate go run main.go

func main() {
    diagram := sequence.NewDiagram(io.Discard).
        Participant("Sophia").
        Participant("David").
        Participant("Subaru").
        LF().
        SyncRequest("Sophia", "David", "Please wake up Subaru").
        SyncResponse("David", "Sophia", "OK").
        LF().
        LoopStart("until Subaru wake up").
        SyncRequest("David", "Subaru", "Wake up!").
        SyncResponse("Subaru", "David", "zzz").
        SyncRequest("David", "Subaru", "Hey!!!").
        BreakStart("if Subaru wake up").
        SyncResponse("Subaru", "David", "......").
        BreakEnd().
        LoopEnd().
        LF().
        SyncResponse("David", "Sophia", "wake up, wake up").
        String()

    markdown.NewMarkdown(os.Stdout).
        H2("Sequence Diagram").
        CodeBlocks(markdown.SyntaxHighlightMermaid, diagram).
        Build()
}

Plain text output: markdown is here

## Sequence Diagram
```mermaid
sequenceDiagram
    participant Sophia
    participant David
    participant Subaru

    Sophia->>David: Please wake up Subaru
    David-->>Sophia: OK

    loop until Subaru wake up
    David->>Subaru: Wake up!
    Subaru-->>David: zzz
    David->>Subaru: Hey!!!
    break if Subaru wake up
    Subaru-->>David: ......
    end
    end

    David-->>Sophia: wake up, wake up


Mermaid output:
```mermaid
sequenceDiagram
    participant Sophia
    participant David
    participant Subaru

    Sophia->>David: Please wake up Subaru
    David-->>Sophia: OK

    loop until Subaru wake up
    David->>Subaru: Wake up!
    Subaru-->>David: zzz
    David->>Subaru: Hey!!!
    break if Subaru wake up
    Subaru-->>David: ......
    end
    end

    David-->>Sophia: wake up, wake up

Entity Relationship Diagram syntax

package main

import (
    "os"

    "github.com/nao1215/markdown"
    "github.com/nao1215/markdown/mermaid/er"
)

//go:generate go run main.go

func main() {
    f, err := os.Create("generated.md")
    if err != nil {
        panic(err)
    }
    defer f.Close()

    teachers := er.NewEntity(
        "teachers",
        []*er.Attribute{
            {
                Type:         "int",
                Name:         "id",
                IsPrimaryKey: true,
                IsForeignKey: false,
                IsUniqueKey:  true,
                Comment:      "Teacher ID",
            },
            {
                Type:         "string",
                Name:         "name",
                IsPrimaryKey: false,
                IsForeignKey: false,
                IsUniqueKey:  false,
                Comment:      "Teacher Name",
            },
        },
    )
    students := er.NewEntity(
        "students",
        []*er.Attribute{
            {
                Type:         "int",
                Name:         "id",
                IsPrimaryKey: true,
                IsForeignKey: false,
                IsUniqueKey:  true,
                Comment:      "Student ID",
            },
            {
                Type:         "string",
                Name:         "name",
                IsPrimaryKey: false,
                IsForeignKey: false,
                IsUniqueKey:  false,
                Comment:      "Student Name",
            },
            {
                Type:         "int",
                Name:         "teacher_id",
                IsPrimaryKey: false,
                IsForeignKey: true,
                IsUniqueKey:  true,
                Comment:      "Teacher ID",
            },
        },
    )
    schools := er.NewEntity(
        "schools",
        []*er.Attribute{
            {
                Type:         "int",
                Name:         "id",
                IsPrimaryKey: true,
                IsForeignKey: false,
                IsUniqueKey:  true,
                Comment:      "School ID",
            },
            {
                Type:         "string",
                Name:         "name",
                IsPrimaryKey: false,
                IsForeignKey: false,
                IsUniqueKey:  false,
                Comment:      "School Name",
            },
            {
                Type:         "int",
                Name:         "teacher_id",
                IsPrimaryKey: false,
                IsForeignKey: true,
                IsUniqueKey:  true,
                Comment:      "Teacher ID",
            },
        },
    )

    erString := er.NewDiagram(f).
        Relationship(
            teachers,
            students,
            er.ExactlyOneRelationship, // "||"
            er.ZeroToMoreRelationship, // "}o"
            er.Identifying,            // "--"
            "Teacher has many students",
        ).
        Relationship(
            teachers,
            schools,
            er.OneToMoreRelationship,  // "|}"
            er.ExactlyOneRelationship, // "||"
            er.NonIdentifying,         // ".."
            "School has many teachers",
        ).
        String()

    err = markdown.NewMarkdown(f).
        H2("Entity Relationship Diagram").
        CodeBlocks(markdown.SyntaxHighlightMermaid, erString).
        Build()

    if err != nil {
        panic(err)
    }
}

Plain text output: markdown is here

## Entity Relationship Diagram
```mermaid
erDiagram
    teachers ||--o{ students : "Teacher has many students"
    teachers }|..|| schools : "School has many teachers"
    schools {
        int id PK,UK "School ID"
        string name  "School Name"
        int teacher_id FK,UK "Teacher ID"
    }
    students {
        int id PK,UK "Student ID"
        string name  "Student Name"
        int teacher_id FK,UK "Teacher ID"
    }
    teachers {
        int id PK,UK "Teacher ID"
        string name  "Teacher Name"
    }


Mermaid output:
```mermaid
erDiagram
    teachers ||--o{ students : "Teacher has many students"
    teachers }|..|| schools : "School has many teachers"
    schools {
        int id PK,UK "School ID"
        string name  "School Name"
        int teacher_id FK,UK "Teacher ID"
    }
    students {
        int id PK,UK "Student ID"
        string name  "Student Name"
        int teacher_id FK,UK "Teacher ID"
    }
    teachers {
        int id PK,UK "Teacher ID"
        string name  "Teacher Name"
    }

Flowchart syntax

package main

import (
    "io"
    "os"

    "github.com/nao1215/markdown"
    "github.com/nao1215/markdown/mermaid/flowchart"
)

//go:generate go run main.go

func main() {
    f, err := os.Create("generated.md")
    if err != nil {
        panic(err)
    }
    defer f.Close()

    fc := flowchart.NewFlowchart(
        io.Discard,
        flowchart.WithTitle("mermaid flowchart builder"),
        flowchart.WithOrientalTopToBottom(),
    ).
        NodeWithText("A", "Node A").
        StadiumNode("B", "Node B").
        SubroutineNode("C", "Node C").
        DatabaseNode("D", "Database").
        LinkWithArrowHead("A", "B").
        LinkWithArrowHeadAndText("B", "D", "send original data").
        LinkWithArrowHead("B", "C").
        DottedLinkWithText("C", "D", "send filtered data").
        String()

    err = markdown.NewMarkdown(f).
        H2("Flowchart").
        CodeBlocks(markdown.SyntaxHighlightMermaid, fc).
        Build()

    if err != nil {
        panic(err)
    }
}

Plain text output: markdown is here

## Flowchart
```mermaid
---
title: mermaid flowchart builder
---
flowchart TB
    A["Node A"]
    B(["Node B"])
    C[["Node C"]]
    D[("Database")]
    A-->B
    B-->|"send original data"|D
    B-->C
    C-. "send filtered data" .-> D


Mermaid output:
```mermaid
flowchart TB
    A["Node A"]
    B(["Node B"])
    C[["Node C"]]
    D[("Database")]
    A-->B
    B-->|"send original data"|D
    B-->C
    C-. "send filtered data" .-> D

Pie chart syntax

package main

import (
    "io"
    "os"

    "github.com/nao1215/markdown"
    "github.com/nao1215/markdown/mermaid/piechart"
)

//go:generate go run main.go

func main() {
    f, err := os.Create("generated.md")
    if err != nil {
        panic(err)
    }
    defer f.Close()

    chart := piechart.NewPieChart(
        io.Discard,
        piechart.WithTitle("mermaid pie chart builder"),
        piechart.WithShowData(true),
    ).
        LabelAndIntValue("A", 10).
        LabelAndFloatValue("B", 20.1).
        LabelAndIntValue("C", 30).
        String()

    err = markdown.NewMarkdown(f).
        H2("Pie Chart").
        CodeBlocks(markdown.SyntaxHighlightMermaid, chart).
        Build()

    if err != nil {
        panic(err)
    }
}

Plain text output: markdown is here

## Pie Chart
```mermaid
%%{init: {"pie": {"textPosition": 0.75}, "themeVariables": {"pieOuterStrokeWidth": "5px"}} }%%
pie showData
    title mermaid pie chart builder
    "A" : 10
    "B" : 20.100000
    "C" : 30


Mermaid output:
```mermaid
%%{init: {"pie": {"textPosition": 0.75}, "themeVariables": {"pieOuterStrokeWidth": "5px"}} }%%
pie showData
    title mermaid pie chart builder
    "A" : 10
    "B" : 20.100000
    "C" : 30

Creating an index for a directory full of markdown files

The markdown package can create an index for Markdown files within the specified directory. This feature was added to generate indexes for Markdown documents produced by nao1215/spectest.

For example, consider the following directory structure:

testdata
├── abc
│   ├── dummy.txt
│   ├── jkl
│   │   └── text.md
│   └── test.md
├── def
│   ├── test.md
│   └── test2.md
├── expected
│   └── index.md
├── ghi
└── test.md

In the following implementation, it creates an index markdown file containing links to all markdown files located within the testdata directory.

        if err := GenerateIndex(
            "testdata", // target directory that contains markdown files
            WithTitle("Test Title"), // title of index markdown
            WithDescription([]string{"Test Description", "Next Description"}), // description of index markdown
        ); err != nil {
            panic(err)
        }

The index Markdown file is created under "target directory/index.md" by default. If you want to change this path, please use the WithWriter() option. The link names in the file will be the first occurrence of H1 or H2 in the target Markdown. If neither H1 nor H2 is present, the link name will be the file name of the destination.

Output:

## Test Title
Test Description

Next Description

### testdata
- [test.md](test.md)

### abc
- [h2 is here](abc/test.md)

### jkl
- [text.md](abc/jkl/text.md)

### def
- [h2 is first, not h1](def/test.md)
- [h1 is here](def/test2.md)

### expected
- [Test Title](expected/index.md)

License

MIT License

Contribution

First off, thanks for taking the time to contribute! See CONTRIBUTING.md for more information. Contributions are not only related to development. For example, GitHub Star motivates me to develop! Please feel free to contribute to this project.