libyaml examples

This is a small set of c language example programs to demonstrate how to use the libyaml library.

Emitter example

emit.c is a basic example to demonstrate how to convert raw c structs to a yaml stream using the libyaml emitter API. The example data to be converted is a list of lists.

struct fruit {
    struct fruit *next;
    char *name;
    char *color;
    int count;
    struct variety *varieties;
};
struct variety {
    struct variety *next;
    char *name;
    char *color;
    bool seedless;
};

These structs are populated with some example data and emitted as yaml:

$ ./emit
---
fruit:
- name: apple
  color: red
  count: 12
  varieties:
  - name: macintosh
    color: red
    seedless: false
  - name: granny smith
    color: green
    seedless: false
  - name: red delicious
    color: red
    seedless: false
- name: orange
  color: orange
  count: 3
  varieties:
  - name: naval
    color: orange
    seedless: false
  - name: clementine
    color: orange
    seedless: true
  - name: valencia
    color: orange
    seedless: false
- name: bannana
  color: yellow
  count: 4
  varieties:
  - name: cavendish
    color: yellow
    seedless: true
  - name: plantain
    color: green
    seedless: true
- name: mango
  color: green
  count: 1
  varieties:
  - name: honey
    color: yellow
    seedless: false
...

Parser example

parser.c is a basic example to demonstrate how to convert a specified yaml grammar to c data structures using the libyaml emitter API. The parser program can read yaml generated by the emit program.

$ cat fruit.yaml
---
fruit:
- name: apple
  color: red
  count: 12
  varieties:
  - name: macintosh
    color: red
    seedless: false
  - name: granny smith
    color: green
    seedless: false
- name: orange
  color: orange
  count: 3
  varieties:
  - name: naval
    color: orange
    seedless: false
  - name: clementine
    color: orange
    seedless: true
...

$ ./parse < fruit.yaml
fruit: name=apple, color=red, count=12
  variety: name=macintosh, color=red, seedless=false
  variety: name=granny smith, color=green, seedless=false
fruit: name=orange, color=orange, count=3
  variety: name=naval, color=orange, seedless=false
  variety: name=clementine, color=orange, seedless=true

Scanner example

scan.c is a general purpose libyaml parser example which scans and prints the libyaml parser events. This can be useful for debugging yaml parsers.

$ ./scan < fruit.yaml
stream-start-event (1)
  document-start-event (3)
    mapping-start-event (9)
      scalar-event (6) = {value="fruit", length=5}
      sequence-start-event (7)
        mapping-start-event (9)
          scalar-event (6) = {value="name", length=4}
          scalar-event (6) = {value="apple", length=5}
          scalar-event (6) = {value="color", length=5}
          scalar-event (6) = {value="red", length=3}
          scalar-event (6) = {value="count", length=5}
          scalar-event (6) = {value="12", length=2}
          scalar-event (6) = {value="varieties", length=9}
          sequence-start-event (7)
            mapping-start-event (9)
              scalar-event (6) = {value="name", length=4}
              scalar-event (6) = {value="macintosh", length=9}
              scalar-event (6) = {value="color", length=5}
              scalar-event (6) = {value="red", length=3}
              scalar-event (6) = {value="seedless", length=8}
              scalar-event (6) = {value="false", length=5}
            mapping-end-event (10)
            mapping-start-event (9)
              scalar-event (6) = {value="name", length=4}
              scalar-event (6) = {value="granny smith", length=12}
              scalar-event (6) = {value="color", length=5}
              scalar-event (6) = {value="green", length=5}
              scalar-event (6) = {value="seedless", length=8}
              scalar-event (6) = {value="false", length=5}
            mapping-end-event (10)
          sequence-end-event (8)
        mapping-end-event (10)
        mapping-start-event (9)
          scalar-event (6) = {value="name", length=4}
          scalar-event (6) = {value="orange", length=6}
          scalar-event (6) = {value="color", length=5}
          scalar-event (6) = {value="orange", length=6}
          scalar-event (6) = {value="count", length=5}
          scalar-event (6) = {value="3", length=1}
          scalar-event (6) = {value="varieties", length=9}
          sequence-start-event (7)
            mapping-start-event (9)
              scalar-event (6) = {value="name", length=4}
              scalar-event (6) = {value="naval", length=5}
              scalar-event (6) = {value="color", length=5}
              scalar-event (6) = {value="orange", length=6}
              scalar-event (6) = {value="seedless", length=8}
              scalar-event (6) = {value="false", length=5}
            mapping-end-event (10)
            mapping-start-event (9)
              scalar-event (6) = {value="name", length=4}
              scalar-event (6) = {value="clementine", length=10}
              scalar-event (6) = {value="color", length=5}
              scalar-event (6) = {value="orange", length=6}
              scalar-event (6) = {value="seedless", length=8}
              scalar-event (6) = {value="true", length=4}
            mapping-end-event (10)
          sequence-end-event (8)
        mapping-end-event (10)
        mapping-start-event (9)
          scalar-event (6) = {value="name", length=4}
          scalar-event (6) = {value="bannana", length=7}
          scalar-event (6) = {value="color", length=5}
          scalar-event (6) = {value="yellow", length=6}
          scalar-event (6) = {value="count", length=5}
          scalar-event (6) = {value="4", length=1}
        mapping-end-event (10)
        mapping-start-event (9)
          scalar-event (6) = {value="name", length=4}
          scalar-event (6) = {value="mango", length=5}
          scalar-event (6) = {value="color", length=5}
          scalar-event (6) = {value="green", length=5}
          scalar-event (6) = {value="count", length=5}
          scalar-event (6) = {value="1", length=1}
        mapping-end-event (10)
      sequence-end-event (8)
    mapping-end-event (10)
  document-end-event (4)
stream-end-event (2)