Terrace/packages/go/docs/recipes.inc.tce

Heading 2 Recipes
  class mt-12

Heading 3 Parse object properties
  class mb-2
Markdown
  Read known properties from a Terrace block and write them to a struct.
CodeBlock go
  package main

  import (
    "fmt"
    "io"
    "strconv"
    "strings"

    "terrace.go"
  )

  type Config struct {
    StringProperty  string
    NumericProperty int
  }

  func main() {
    input := `object
    string_property An example string
    numeric_property 42`

    reader := &StringReader{reader: strings.NewReader(input)}
    doc := terrace.NewTerraceDocument(reader, ' ')

    config := Config{}

    for {
      node, err := doc.Next()
      if err == io.EOF {
        break
      }
      if err != nil {
        panic(err)
      }

      if node.Head() == "object" {
        objectLevel := node.Level()
        for {
          node, err := doc.Next()
          if err == io.EOF {
            break
          }
          if err != nil {
            panic(err)
          }
          if node.Level() <= objectLevel {
            // We've exited the object block
            break
          }

          switch node.Head() {
          case "string_property":
            config.StringProperty = node.Tail()
          case "numeric_property":
            if val, err := strconv.Atoi(node.Tail()); err == nil {
              config.NumericProperty = val
            }
          }
        }
      }
    }

    fmt.Printf("%+v\n", config)
    // {StringProperty:An example string NumericProperty:42}
  }

Markdown
  Read *all* properties as strings from a Terrace block and write them to a map.
CodeBlock go
  package main

  import (
    "fmt"
    "io"
    "strings"

    "terrace.go"
  )

  func main() {
    input := `object
    property1 Value 1
    property2 Value 2
    random_property igazi3ii4quaC5OdoB5quohnah1beeNg`

    reader := &StringReader{reader: strings.NewReader(input)}
    doc := terrace.NewTerraceDocument(reader, ' ')

    output := make(map[string]string)

    for {
      node, err := doc.Next()
      if err == io.EOF {
        break
      }
      if err != nil {
        panic(err)
      }

      if node.Head() == "object" {
        objectLevel := node.Level()
        for {
          node, err := doc.Next()
          if err == io.EOF {
            break
          }
          if err != nil {
            panic(err)
          }
          if node.Level() <= objectLevel {
            // We've exited the object block
            break
          }

          // Skip empty lines
          if node.Content() == "" {
            continue
          }
          // Add any properties to the map as strings using the
          // line Head() as the key and Tail() as the value
          output[node.Head()] = node.Tail()
        }
      }
    }

    fmt.Printf("%+v\n", output)
    // map[property1:Value 1 property2:Value 2 random_property:igazi3ii4quaC5OdoB5quohnah1beeNg]
  }

Heading 3 Process nested blocks
  class mb-2
Markdown
  Handle hierarchically nested blocks with recursive processing.
CodeBlock go
  package main

  import (
    "fmt"
    "io"
    "strings"

    "terrace.go"
  )

  type Block struct {
    Name     string
    Content  string
    Children []Block
  }

  func parseBlock(doc *terrace.TerraceDocument, parentLevel int) []Block {
    var blocks []Block

    for {
      node, err := doc.Next()
      if err == io.EOF {
        break
      }
      if err != nil {
        panic(err)
      }

      // If we've returned to the parent level or higher, we're done
      if node.Level() <= parentLevel {
        break
      }

      block := Block{
        Name:    node.Head(),
        Content: node.Tail(),
      }

      // Parse any nested children
      block.Children = parseBlock(doc, node.Level())
      blocks = append(blocks, block)
    }

    return blocks
  }

  func main() {
    input := `root
    section1 Section 1 Content
      subsection1 Subsection 1 Content
      subsection2 Subsection 2 Content
    section2 Section 2 Content
      nested
        deeply Nested Content`

    reader := &StringReader{reader: strings.NewReader(input)}
    doc := terrace.NewTerraceDocument(reader, ' ')

    blocks := parseBlock(doc, -1)
    
    fmt.Printf("%+v\n", blocks)
  }