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Merged
merged 4 commits into from
Nov 25, 2024
Merged

First and last #1067

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f8ce4d0
Add first and last functions to the lists extension.
bigkevmcd Nov 1, 2024
5b59ddc
Make Optional Optional.
bigkevmcd Nov 13, 2024
8128e0b
Move first and last to the optional package.
bigkevmcd Nov 20, 2024
568b432
Update documentation for list/first.
bigkevmcd Nov 23, 2024
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4 changes: 4 additions & 0 deletions cel/cel_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -2735,6 +2735,10 @@ func TestOptionalValuesEval(t *testing.T) {
RepeatedString: []string{"greetings", "world"},
},
},
{expr: `[].first()`, out: types.OptionalNone},
{expr: `['a','b','c'].first()`, out: types.OptionalOf(types.String("a"))},
{expr: `[].last()`, out: types.OptionalNone},
{expr: `[1, 2, 3].last()`, out: types.OptionalOf(types.Int(3))},
}

for i, tst := range tests {
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54 changes: 54 additions & 0 deletions cel/library.go
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Expand Up @@ -260,6 +260,27 @@ func (stdLibrary) ProgramOptions() []ProgramOption {
// be expressed with `optMap`.
//
// msg.?elements.optFlatMap(e, e[?0]) // return the first element if present.

// # First
//
// Introduced in version: 2
//
// Returns an optional with the first value from the right hand list, or
// optional.None.
//
// [1, 2, 3].first().value() == 1

// # Last
//
// Introduced in version: 2
//
// Returns an optional with the last value from the right hand list, or
// optional.None.
//
// [1, 2, 3].last().value() == 3
//
// This is syntactic sugar for msg.elements[msg.elements.size()-1].

func OptionalTypes(opts ...OptionalTypesOption) EnvOption {
lib := &optionalLib{version: math.MaxUint32}
for _, opt := range opts {
Expand Down Expand Up @@ -375,6 +396,39 @@ func (lib *optionalLib) CompileOptions() []EnvOption {
if lib.version >= 1 {
opts = append(opts, Macros(ReceiverMacro(optFlatMapMacro, 2, optFlatMap)))
}

if lib.version >= 2 {
opts = append(opts, Function("last",
MemberOverload("list_last", []*Type{listTypeV}, optionalTypeV,
UnaryBinding(func(v ref.Val) ref.Val {
list := v.(traits.Lister)
sz := list.Size().Value().(int64)

if sz == 0 {
return types.OptionalNone
}

return types.OptionalOf(list.Get(types.Int(sz - 1)))
}),
),
))

opts = append(opts, Function("first",
MemberOverload("list_first", []*Type{listTypeV}, optionalTypeV,
UnaryBinding(func(v ref.Val) ref.Val {
list := v.(traits.Lister)
sz := list.Size().Value().(int64)

if sz == 0 {
return types.OptionalNone
}

return types.OptionalOf(list.Get(types.Int(0)))
}),
),
))
}

return opts
}

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30 changes: 30 additions & 0 deletions ext/README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -500,6 +500,36 @@ Examples:
].sortBy(e, e.score).map(e, e.name)
== ["bar", "foo", "baz"]

### Last

**Introduced in the OptionalTypes library version 2**

Returns an optional with the last value from the list or `optional.None` if the
list is empty.

<list(T)>.list() -> <Optional(T)>

Examples:

[1, 2, 3].list().value() == 3
[].last().orValue('test') == 'test'

This is syntactic sugar for list[list.size()-1].

### First

**Introduced in the OptionalTypes library version 2**

Returns an optional with the first value from the list or `optional.None` if the
list is empty.

<list(T)>.first() -> <Optional(T)>

Examples:

[1, 2, 3].first().value() == 1
[].first().orValue('test') == 'test'

## Sets

Sets provides set relationship tests.
Expand Down