YAML 语法

--- # document start

# Comments in YAML look like this.

# YAML supports single-line comments.

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# SCALAR TYPES

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# Our root object (which continues for the entire document) will be a map,

# which is equivalent to a dictionary, hash or object in other languages.

key: value another_key: Another value goes here. a_number_value: 100 scientific_notation: 1e+12 hex_notation: 0x123 # evaluates to 291 octal_notation: 0123 # evaluates to 83

# The number 1 will be interpreted as a number, not a boolean.

# If you want it to be interpreted as a boolean, use true.

boolean: true null_value: null another_null_value: ~ key with spaces: value

# Yes and No (doesn't matter the case) will be evaluated to boolean

# true and false values respectively.

# To use the actual value use single or double quotes.

no: no # evaluates to "no": false yes: No # evaluates to "yes": false not_enclosed: yes # evaluates to "not_enclosed": true enclosed: 'yes' # evaluates to "enclosed": yes

# Notice that strings don't need to be quoted. However, they can be.

however: 'A string, enclosed in quotes.' 'Keys can be quoted too.': "Useful if you want to put a ':' in your key." single quotes: "have 'one' escape pattern" double quotes: "have many: \", \0, \t, \u263A, \x0d\x0a == \r\n, and more."

# UTF-8/16/32 characters need to be encoded

Superscript two: \u00B2

# Special characters must be enclosed in single or double quotes

special_characters: '[ John ] & { Jane } - <Doe>'

# Multiple-line strings can be written either as a 'literal block' (using |),

# or a 'folded block' (using '>').

# Literal block turn every newline within the string into a literal newline (\n).

# Folded block removes newlines within the string.

literal_block: | This entire block of text will be the value of the 'literal_block' key, with line breaks being preserved.

The literal continues until de-dented, and the leading indentation is stripped.

      Any lines that are 'more-indented' keep the rest of their indentation -
      these lines will be indented by 4 spaces.

folded_style: > This entire block of text will be the value of 'folded_style', but this time, all newlines will be replaced with a single space.

Blank lines, like above, are converted to a newline character.

      'More-indented' lines keep their newlines, too -
      this text will appear over two lines.

# |- and >- removes the trailing blank lines (also called literal/block "strip")

literal_strip: |- This entire block of text will be the value of the 'literal_strip' key, with trailing blank line being stripped. block_strip: >- This entire block of text will be the value of 'block_strip', but this time, all newlines will be replaced with a single space and trailing blank line being stripped.

# |+ and >+ keeps trailing blank lines (also called literal/block "keep")

literal_keep: |+ This entire block of text will be the value of the 'literal_keep' key, with trailing blank line being kept.

block_keep: >+ This entire block of text will be the value of 'block_keep', but this time, all newlines will be replaced with a single space and trailing blank line being kept.

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# COLLECTION TYPES

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# Nesting uses indentation. 2 space indent is preferred (but not required).

a_nested_map: key: value another_key: Another Value another_nested_map: hello: hello

# Maps don't have to have string keys.

0.25: a float key

# Keys can also be complex, like multi-line objects

# We use ? followed by a space to indicate the start of a complex key.

? | This is a key that has multiple lines : and this is its value

# YAML also allows mapping between sequences with the complex key syntax

# Some language parsers might complain

# An example

? - Manchester United

- Real Madrid : [2001-01-01, 2002-02-02]

# Sequences (equivalent to lists or arrays) look like this

# (note that the '-' counts as indentation):

a_sequence:

- Item 1
- Item 2
- 0.5 # sequences can contain disparate types.
- Item 4
- key: value another_key: another_value
- - This is a sequence
  - inside another sequence
- - - Nested sequence indicators
    - can be collapsed

# Since YAML is a superset of JSON, you can also write JSON-style maps and

# sequences:

json_map: {'key': 'value'} json_seq: [3, 2, 1, 'takeoff'] and quotes are optional: {key: [3, 2, 1, takeoff]}

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# EXTRA YAML FEATURES

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# YAML also has a handy feature called 'anchors', which let you easily duplicate

# content across your document.

# Anchors identified by & character which define the value.

# Aliases identified by \* character which acts as "see above" command.

# Both of these keys will have the same value:

anchored_content: &anchor_name This string will appear as the value of two keys. other_anchor: \*anchor_name

# Anchors can be used to duplicate/inherit properties

base: &base name: Everyone has same name

# The expression << is called 'Merge Key Language-Independent Type'. It is used to

# indicate that all the keys of one or more specified maps should be inserted

# into the current map.

# NOTE: If key already exists alias will not be merged

foo: <<: *base # doesn't merge the anchor age: 10 name: John bar: <<: *base # base anchor will be merged age: 20

# foo name won't be changed and it will be: John. On the other hand, bar's name will be changed to the base one: Everyone has same name

# YAML also has tags, which you can use to explicitly declare types.

# Syntax: !![typeName] [value]

explicit_boolean: !!bool true explicit_integer: !!int 42 explicit_float: !!float -42.24 explicit_string: !!str 0.5 explicit_datetime: !!timestamp 2022-11-17 12:34:56.78 +9 explicit_null: !!null null

# Some parsers implement language specific tags, like this one for Python's

# complex number type.

python_complex_number: !!python/complex 1+2j

# We can also use yaml complex keys with language specific tags

!!python/tuple [5, 7]: Fifty Seven

# Would be {(5, 7): 'Fifty Seven'} in Python

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# EXTRA YAML TYPES

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# Strings and numbers aren't the only scalars that YAML can understand.

# ISO-formatted date and datetime literals are also parsed.

datetime_canonical: 2001-12-15T02:59:43.1Z datetime_space_separated_with_time_zone: 2001-12-14 21:59:43.10 -5 date_implicit: 2002-12-14 date_explicit: !!timestamp 2002-12-14

# The !!binary tag indicates that a string is actually a base64-encoded

# representation of a binary blob.

gif_file: !!binary | R0lGODlhDAAMAIQAAP//9/X17unp5WZmZgAAAOfn515eXvPz7Y6OjuDg4J+fn5 OTk6enp56enmlpaWNjY6Ojo4SEhP/++f/++f/++f/++f/++f/++f/++f/++f/+ +f/++f/++f/++f/++f/++SH+Dk1hZGUgd2l0aCBHSU1QACwAAAAADAAMAAAFLC AgjoEwnuNAFOhpEMTRiggcz4BNJHrv/zCFcLiwMWYNG84BwwEeECcgggoBADs=

# YAML also has a set type, which looks like this:

set: item1: item2: item3: or: {item1, item2, item3}

# Sets are just maps with null values; the above is equivalent to:

set2: item1: null item2: null item3: null ... # document end