YAML Schemas in YAML::PP

YAML Test Suite Test Cases | Schema examples | Schema comparison

This is a comparison of the different YAML Schemas and how the Perl module YAML::PP implements them.

YAML 1.2 Failsafe Schema

Regular expression	Resolved to tag
/* Empty */	tag:yaml.org,2002:str
.*	tag:yaml.org,2002:str (Default)

YAML 1.2 JSON Schema

Regular expression	Resolved to tag
true \| false	tag:yaml.org,2002:bool
-? ( 0 \| [1-9] [0-9]* )	tag:yaml.org,2002:int
-? ( 0 \| [1-9] [0-9]* ) ( \. [0-9]* )? ( [eE] [-+]? [0-9]+ )?	tag:yaml.org,2002:float
null	tag:yaml.org,2002:null
Official
/* Empty */	Error
.*	Error
YAML::PP (option empty=str (default))
/* Empty */	tag:yaml.org,2002:str
.*	tag:yaml.org,2002:str (Default)
YAML::PP (option empty=null)
/* Empty */	tag:yaml.org,2002:null
.*	tag:yaml.org,2002:str (Default)

YAML 1.2 Core Schema

Regular expression	Resolved to tag
true \| True \| TRUE \| false \| False \| FALSE	tag:yaml.org,2002:bool
0o [0-7]+	tag:yaml.org,2002:int (Base 8)
[-+]? [0-9]+	tag:yaml.org,2002:int (Base 10)
0x [0-9a-fA-F]+	tag:yaml.org,2002:int (Base 16)
[-+]? ( \. [0-9]+ \| [0-9]+ ( \. [0-9]* )? ) ( [eE] [-+]? [0-9]+ )?	tag:yaml.org,2002:float (Number)
[-+]? \. ( inf \| Inf \| INF )	tag:yaml.org,2002:float (Infinity)
\. ( nan \| NaN \|NAN )	tag:yaml.org,2002:float (Not a number)
null \| Null \| NULL \| ~	tag:yaml.org,2002:null
/* Empty */	tag:yaml.org,2002:null
.*	tag:yaml.org,2002:str (Default)

YAML 1.1 Types

Regular expression	Resolved to tag
y\|Y\|yes\|Yes\|YES\|n\|N\|no\|No\|NO\|true\|True\|TRUE\|false\|False\|FALSE\|on\|On\|ON\|off\|Off\|OFF	tag:yaml.org,2002:bool
[-+]? 0b [0-1_]+	tag:yaml.org,2002:int (Base 2)
[-+]? 0 [0-7_]+	tag:yaml.org,2002:int (Base 8)
[-+]? ( 0 \| [1-9] [0-9_]* )	tag:yaml.org,2002:int (Base 10)
[-+]? 0x [0-9a-fA-F_]+	tag:yaml.org,2002:int (Base 16)
[-+]? [1-9] [0-9_]* ( : [0-5]? [0-9] )+	tag:yaml.org,2002:int (Base 60)
[-+]? ( [0-9] [0-9_]* )? \. [0-9.]* ( [eE] [-+] [0-9]+ )?	tag:yaml.org,2002:float (Base 10)
[-+]? [0-9] [0-9_]* ( : [0-5]? [0-9] )+ \. [0-9_ ]*	tag:yaml.org,2002:float (Base 60)
[-+]? \. ( inf \| Inf \| INF )	tag:yaml.org,2002:float (Infinity)
\. ( nan \| NaN \|NAN )	tag:yaml.org,2002:float (Not a number)
null \| Null \| NULL \| ~	tag:yaml.org,2002:null
/* Empty */	tag:yaml.org,2002:null
.*	tag:yaml.org,2002:str (Default)

There are more types not listed here for YAML 1.1 (like '!!timestamp', '!!binary', '!!merge').