Plugin: yaypeg

• infos = Information about the yaypeg plugin is in keys below
• infos/author = René Schwaiger sanss.nosp@m.ecou.nosp@m.rs@me.nosp@m..com
• infos/licence = BSD
• infos/needs = directoryvalue yamlsmith
• infos/provides = storage/yaml
• infos/recommends =
• infos/placements = getstorage
• infos/status = maintained unittest preview experimental unfinished nodoc concept discouraged
• infos/metadata =
• infos/description = This storage plugin uses a PEG based parser to read YAML files

YAy PEG

The YAy PEG plugin use a parser based on PEGTL to convert YAML data to Elektra’s KeySet type.

Dependencies

This plugin requires PEGTL 2.7.1 or later. It does not support PEGTL 3, which requires C++ 17.

Examples

Mappings

```

Mount plugin

sudo kdb mount config.yaml user/tests/yaypeg yaypeg

Add some values

kdb set user/tests/yaypeg/movements/deadly 'Dull' kdb set user/tests/yaypeg/movements/deep 'Red'

Manually add a key

printf 'Rosalía: El::Mal::Querer' >> kdb file user/tests/yaypeg

List keys

kdb ls user/tests/yaypeg #> user/tests/yaypeg/Rosalía #> user/tests/yaypeg/movements/deadly #> user/tests/yaypeg/movements/deep

Retrieve a value

kdb get user/tests/yaypeg/Rosalía #> El::Mal::Querer

Undo modifications

kdb rm -r user/tests/yaypeg sudo kdb umount user/tests/yaypeg

### Arrays

Mount plugin

sudo kdb mount config.yaml user/tests/yaypeg yaypeg

Manually add some values

printf 'ponies:
' > kdb file user/tests/yaypeg printf ' - Fluttershy # Yay!
' >> kdb file user/tests/yaypeg printf ' - Pinkie Pie
' >> kdb file user/tests/yaypeg printf ' - Maud Pie' >> kdb file user/tests/yaypeg

List array keys

kdb ls user/tests/yaypeg #> user/tests/yaypeg/ponies #> user/tests/yaypeg/ponies/#0 #> user/tests/yaypeg/ponies/#1 #> user/tests/yaypeg/ponies/#2

Retrieve last array entry

kdb get user/tests/yaypeg/ponies/$(kdb getmeta user/tests/yaypeg/ponies array) #> Maud Pie

Undo modifications

kdb rm -r user/tests/yaypeg sudo kdb umount user/tests/yaypeg

### Boolean Values

Mount plugin

sudo kdb mount config.yaml user/tests/yaypeg yaypeg

Manually add a boolean value to the database

printf 'one: true' > kdb file user/tests/yaypeg

Elektra stores boolean values as 0 and 1

kdb get user/tests/yaypeg/one #> 1

Undo modifications to the key database

kdb rm -r user/tests/yaypeg sudo kdb umount user/tests/yaypeg

### Error Messages

Mount plugin

sudo kdb mount config.yaml user/tests/yaypeg yaypeg

Manually add syntactically incorrect data

printf 'Fluttershy:
' > kdb file user/tests/yaypeg printf 'I’d like to be a tree
' >> kdb file user/tests/yaypeg # Incorrect indentation

kdb ls user/tests/yaypeg

RET: 5

STDERR: .*config.yaml:2:0: Incomplete document, expected “end of file”.*

Let us look at the error message more closely.

Since the location of config.yaml depends on the current user and OS,

we store the text before config.yaml as user/tests/error/prefix.

kdb set user/tests/error "$(2>&1 kdb ls user/tests/yaypeg)" kdb set user/tests/error/prefix "$(kdb get user/tests/error | grep 'config.yaml' | head -1 | sed -E 's/(.*)config.yaml.*/\1/')"

We also store the length of the prefix, so we can remove it from every

line of the error message.

kdb set user/tests/error/prefix/length "$(kdb get user/tests/error/prefix | wc -c | sed 's/[ ]*//g')"

Since we only want to look at the “reason” of the error, we

remove the other part of the error message with head and tail.

kdb get user/tests/error | tail -n3 | cut -c"$(kdb get user/tests/error/prefix/length)"- #> config.yaml:2:0: Incomplete document, expected “end of file” #> I’d like to be a tree #> ^

Fix syntax error

printf 'Fluttershy:
' > kdb file user/tests/yaypeg printf ' I’d like to be a tree
' >> kdb file user/tests/yaypeg

kdb get user/tests/yaypeg/Fluttershy #> I’d like to be a tree

Add double quoted scalar with missing closing quote character

printf '"nothing,nowhere.' > kdb file user/tests/yaypeg kdb ls user/tests/yaypeg

RET: 5

STDERR: .*config.yaml:1:17: Missing closing double quote or incorrect value inside flow scalar.*

Check error messages for other syntax errors

printf '"\ö"' > kdb file user/tests/yaypeg kdb ls user/tests/yaypeg

RET: 5

STDERR: .*config.yaml:1:2: Unexpected escape character.*

printf "\"\07"" > kdb file user/tests/yaypeg kdb ls user/tests/yaypeg

RET: 5

STDERR: .*config.yaml:1:1: Missing closing double quote or incorrect value inside flow scalar.*

printf "'Single" > kdb file user/tests/yaypeg kdb ls user/tests/yaypeg

RET: 5

STDERR: .*config.yaml:1:7: Missing closing single quote or incorrect value inside flow scalar.*

printf "'\07'" > kdb file user/tests/yaypeg kdb ls user/tests/yaypeg

RET: 5

STDERR: .*config.yaml:1:1: Missing closing single quote or incorrect value inside flow scalar.*

Store syntactically correct data

printf 'dummy' > kdb file user/tests/yaypeg

Undo modifications

kdb rm -r user/tests/error kdb rm -r user/tests/yaypeg sudo kdb umount user/tests/yaypeg ```

Limitations

• The plugin does not support

  • block scalars,
  • flow collections,
  • tags,
  • anchors & aliases, and
  • multiple documents

  Comments

While the parser does read comments, the listener does currently not add metakeys for them. This means that comments will be lost, if you modify a key set.

Error Messages

Visualized error messages (containing ^ markers) might not point to the correct error location, if the input contains tabs or unicode characters with a length other than 1.