Heading 2 Reader API
  class mt-12
Markdown
  The [Document API](#document-api) requires a `Reader` interface to iterate through lines
  in a document. A `Reader` has a `Read()` method that returns a string and an error. Each time it is called, it returns the next line from whichever source it is pulling them.

  Terrace for Go does not provide built-in readers, but you can easily create your own.

Heading 3 Reader
  class mb-4 mt-12
Markdown
  An interface with a `Read()` method that returns the next line in a document and an error. The error should be `io.EOF` when the end of the document has been reached.

CodeBlock go
  // Interface Definition
  type Reader interface {
    Read() (string, error)
  }

Heading 3 StringReader
  class mb-4 mt-12
Markdown
  You can implement a `Reader` that reads from a string.

CodeBlock go
  import (
    "io"
    "strings"
  )

  type StringReader struct {
    reader *strings.Reader
  }

  func (r *StringReader) Read() (string, error) {
    line, err := r.reader.ReadString('\n')
    if err != nil {
      return "", err
    }
    return strings.TrimRight(line, "\n"), nil
  }

Markdown
  **Usage**
CodeBlock go
  import (
    "fmt"
    "io"
    "strings"

    "terrace.go"
  )

  func main() {
    data := `
      title Example Title
        line 2
    `
    reader := &StringReader{reader: strings.NewReader(data)}
    doc := terrace.NewTerraceDocument(reader, ' ')

    for {
      node, err := doc.Next()
      if err == io.EOF {
        break
      }
      if err != nil {
        panic(err)
      }
      fmt.Printf("%d %s\n", node.Level(), node.Content())
    }
  }

Heading 3 FileReader
  class mb-4 mt-12
Markdown
  You can use the `bufio` package to create a `Reader` for a file.

CodeBlock go
  import (
    "bufio"
    "os"
  )

  type FileReader struct {
    scanner *bufio.Scanner
  }

  func NewFileReader(file *os.File) *FileReader {
    return &FileReader{scanner: bufio.NewScanner(file)}
  }

  func (r *FileReader) Read() (string, error) {
    if r.scanner.Scan() {
      return r.scanner.Text(), nil
    }
    if err := r.scanner.Err(); err != nil {
      return "", err
    }
    return "", io.EOF
  }