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Add filter, map and reduce to Array #38645

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May 6, 2021
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73 changes: 73 additions & 0 deletions core/variant/array.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -361,6 +361,79 @@ Array Array::slice(int p_begin, int p_end, int p_step, bool p_deep) const { // l
return new_arr;
}

Array Array::filter(const Callable &p_callable) const {
Array new_arr;
new_arr.resize(size());
int accepted_count = 0;

for (int i = 0; i < size(); i++) {
const Variant **argptrs = (const Variant **)alloca(sizeof(Variant *));
argptrs[0] = &get(i);

Variant result;
Callable::CallError ce;
p_callable.call(argptrs, 1, result, ce);
if (ce.error != Callable::CallError::CALL_OK) {
ERR_FAIL_V_MSG(Array(), "Error calling method from 'filter': " + Variant::get_callable_error_text(p_callable, argptrs, 1, ce));
}

if (result.operator bool()) {
new_arr[accepted_count] = get(i);
accepted_count++;
}
}

new_arr.resize(accepted_count);

return new_arr;
}

Array Array::map(const Callable &p_callable) const {
Array new_arr;
new_arr.resize(size());

for (int i = 0; i < size(); i++) {
const Variant **argptrs = (const Variant **)alloca(sizeof(Variant *));
argptrs[0] = &get(i);

Variant result;
Callable::CallError ce;
p_callable.call(argptrs, 1, result, ce);
if (ce.error != Callable::CallError::CALL_OK) {
ERR_FAIL_V_MSG(Array(), "Error calling method from 'map': " + Variant::get_callable_error_text(p_callable, argptrs, 1, ce));
}

new_arr[i] = result;
}

return new_arr;
}

Variant Array::reduce(const Callable &p_callable, const Variant &p_accum) const {
int start = 0;
Variant ret = p_accum;
if (ret == Variant() && size() > 0) {
ret = front();
start = 1;
}

for (int i = start; i < size(); i++) {
const Variant **argptrs = (const Variant **)alloca(sizeof(Variant *) * 2);
argptrs[0] = &ret;
argptrs[1] = &get(i);

Variant result;
Callable::CallError ce;
p_callable.call(argptrs, 2, result, ce);
if (ce.error != Callable::CallError::CALL_OK) {
ERR_FAIL_V_MSG(Variant(), "Error calling method from 'reduce': " + Variant::get_callable_error_text(p_callable, argptrs, 2, ce));
}
ret = result;
}

return ret;
}

struct _ArrayVariantSort {
_FORCE_INLINE_ bool operator()(const Variant &p_l, const Variant &p_r) const {
bool valid = false;
Expand Down
3 changes: 3 additions & 0 deletions core/variant/array.h
Original file line number Diff line number Diff line change
Expand Up @@ -101,6 +101,9 @@ class Array {
Array duplicate(bool p_deep = false) const;

Array slice(int p_begin, int p_end, int p_step = 1, bool p_deep = false) const;
Array filter(const Callable &p_callable) const;
Array map(const Callable &p_callable) const;
Variant reduce(const Callable &p_callable, const Variant &p_accum) const;

bool operator<(const Array &p_array) const;
bool operator<=(const Array &p_array) const;
Expand Down
3 changes: 3 additions & 0 deletions core/variant/variant_call.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -1666,6 +1666,9 @@ static void _register_variant_builtin_methods() {
bind_method(Array, reverse, sarray(), varray());
bind_method(Array, duplicate, sarray("deep"), varray(false));
bind_method(Array, slice, sarray("begin", "end", "step", "deep"), varray(1, false));
bind_method(Array, filter, sarray("method"), varray());
bind_method(Array, map, sarray("method"), varray());
bind_method(Array, reduce, sarray("method", "accum"), varray(Variant()));
bind_method(Array, max, sarray(), varray());
bind_method(Array, min, sarray(), varray());

Expand Down
53 changes: 53 additions & 0 deletions doc/classes/Array.xml
Original file line number Diff line number Diff line change
Expand Up @@ -258,6 +258,23 @@
[/codeblocks]
</description>
</method>
<method name="filter" qualifiers="const">
<return type="Array">
</return>
<argument index="0" name="method" type="Callable">
</argument>
<description>
Calls the provided [Callable] for each element in array and removes all elements for which the method returned [code]false[/code].
[codeblock]
func _ready():
print([1, 2, 3].filter(remove_1)) # Prints [2, 3].
print([1, 2, 3].filter(func(number): return number != 1)) # Same as above, but using lambda function.

func remove_1(number):
return number != 1
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[/codeblock]
</description>
</method>
<method name="find" qualifiers="const">
<return type="int">
</return>
Expand Down Expand Up @@ -356,6 +373,23 @@
Returns [code]true[/code] if the array is empty.
</description>
</method>
<method name="map" qualifiers="const">
<return type="Array">
</return>
<argument index="0" name="method" type="Callable">
</argument>
<description>
Calls the provided [Callable] for each element in array and replaces them with return value of the method.
[codeblock]
func _ready():
print([1, 2, 3].map(negate)) # Prints [-1, -2, -3].
print([1, 2, 3].map(func(number): return -number)) # Same as above, but using lambda function.

func negate(number):
return -number
[/codeblock]
</description>
</method>
<method name="max" qualifiers="const">
<return type="Variant">
</return>
Expand Down Expand Up @@ -468,6 +502,25 @@
[b]Note:[/b] On large arrays, this method is much slower than [method push_back] as it will reindex all the array's elements every time it's called. The larger the array, the slower [method push_front] will be.
</description>
</method>
<method name="reduce" qualifiers="const">
<return type="Variant">
</return>
<argument index="0" name="method" type="Callable">
</argument>
<argument index="1" name="accum" type="Variant" default="null">
</argument>
<description>
Calls the provided [Callable] for each element in array and accumulates the result in [code]accum[/code]. The method for [Callable] takse two arguments: current value of [code]accum[/code] and the current array element. If [code]accum[/code] is [code]null[/code] (default value), the method will use first element from the array as initial value.
[codeblock]
func _ready():
print([1, 2, 3].reduce(factorial, 1)) # Prints 6.
print([1, 2, 3].reduce(func(accum, number): return accum * number)) # Same as above, but using lambda function.

func factorial(accum, number):
return accum * number
[/codeblock]
</description>
</method>
<method name="remove">
<return type="void">
</return>
Expand Down