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Add filter operation #1588

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merged 7 commits into from Mar 8, 2023
Merged

Add filter operation #1588

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69a6785
add filter operation
rbren Mar 6, 2023
b554a5b
add tests
rbren Mar 6, 2023
c5919c4
add tests
rbren Mar 6, 2023
38187c0
revert debug
rbren Mar 6, 2023
6cd9d8c
simplify filter
rbren Mar 7, 2023
98c45ed
fix tests
rbren Mar 7, 2023
65f4b15
remove logs
rbren Mar 7, 2023
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18 changes: 18 additions & 0 deletions pkg/yqlib/doc/operators/filter.md
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@@ -0,0 +1,18 @@

## Filter array
Given a sample.yml file of:
```yaml
- 1
- 2
- 3
```
then
```bash
yq 'filter(. < 3)' sample.yml
```
will output
```yaml
- 1
- 2
```

1 change: 1 addition & 0 deletions pkg/yqlib/lexer_participle.go
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Expand Up @@ -37,6 +37,7 @@ var participleYqRules = []*participleYqRule{

{"MapValues", `map_?values`, opToken(mapValuesOpType), 0},
simpleOp("map", mapOpType),
simpleOp("filter", filterOpType),
simpleOp("pick", pickOpType),

{"FlattenWithDepth", `flatten\([0-9]+\)`, flattenWithDepth(), 0},
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1 change: 1 addition & 0 deletions pkg/yqlib/lib.go
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Expand Up @@ -84,6 +84,7 @@ var expressionOpType = &operationType{Type: "EXP", NumArgs: 0, Precedence: 50, H

var collectOpType = &operationType{Type: "COLLECT", NumArgs: 1, Precedence: 50, Handler: collectOperator}
var mapOpType = &operationType{Type: "MAP", NumArgs: 1, Precedence: 50, Handler: mapOperator}
var filterOpType = &operationType{Type: "FILTER", NumArgs: 1, Precedence: 50, Handler: filterOperator}
var errorOpType = &operationType{Type: "ERROR", NumArgs: 1, Precedence: 50, Handler: errorOperator}
var pickOpType = &operationType{Type: "PICK", NumArgs: 1, Precedence: 50, Handler: pickOperator}
var evalOpType = &operationType{Type: "EVAL", NumArgs: 1, Precedence: 50, Handler: evalOperator}
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56 changes: 56 additions & 0 deletions pkg/yqlib/operator_filter.go
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@@ -0,0 +1,56 @@
package yqlib

import (
"errors"
"container/list"
)

func filterOperator(d *dataTreeNavigator, context Context, expressionNode *ExpressionNode) (Context, error) {
log.Debugf("-- filterOperation")
var results = list.New()

for el := context.MatchingNodes.Front(); el != nil; el = el.Next() {
candidate := el.Value.(*CandidateNode)
children := context.SingleChildContext(candidate)
splatted, err := splat(children, traversePreferences{})
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if err != nil {
return Context{}, err
}

if err != nil {
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return Context{}, err
}

for resultEl := splatted.MatchingNodes.Front(); resultEl != nil; resultEl = resultEl.Next() {
result := resultEl.Value.(*CandidateNode)
childCtx := context.SingleReadonlyChildContext(result)
include, err := d.GetMatchingNodes(childCtx, expressionNode.RHS)
if err != nil {
return Context{}, err
}
var includeResult bool
var errDecoding error
includeEl := include.MatchingNodes.Front()
if includeEl.Next() != nil {
return Context{}, errors.New("Only expected one child")
}
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This was the best way I could find to turn each value into a truthy value to determine if it should be included. LMK if there's a better way

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hmm, yeah there should be a cleaner way. What this function is basically doing is a map(select(X)).

You could create a new select expression node and give the expression.RHS to it.

something like:

    selectNodesOp := &ExpressionNode{
      Operation: selectOp,
      RHS:       expression.RHS,
      }
      
      includedNodes, err := d.GetMatchingNodes(splatted, selectNodesOp.RHS)

Pretty sure this could be extended to create a map(select) expression and just delegate the logic to those functions entirely...

includeVal := includeEl.Value.(*CandidateNode)
includeResult, errDecoding = isTruthy(includeVal)
if errDecoding != nil {
return Context{}, errDecoding
}
log.Debug("isTruthy %v", includeResult)
if includeResult {
selfExpression := &ExpressionNode{Operation: &Operation{OperationType: selfReferenceOpType}}
collected, err := collectTogether(d, childCtx, selfExpression)
if err != nil {
return Context{}, err
}
collected.Node.Style = unwrapDoc(result.Node).Style
results.PushBack(collected)
}
}
}
return context.ChildContext(results), nil
}

49 changes: 49 additions & 0 deletions pkg/yqlib/operator_filter_test.go
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@@ -0,0 +1,49 @@
package yqlib

import (
"testing"
)

var filterOperatorScenarios = []expressionScenario{
{
description: "Filter array",
document: `[1,2,3]`,
expression: `filter(. < 3)`,
expected: []string{
"D0, P[], (!!seq)::- 1\n",
"D0, P[], (!!seq)::- 2\n",
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this isn't actually the right result - this means the filter function is return two arrays - each with a single element. It should return a single array with two elements

"D0, P[], (!!seq)::- 1\n- 2\n",

I think if you refactor to use map and select under the hood - it would do the right thing.

},
},
{
skipDoc: true,
document: `[1,2,3]`,
expression: `filter(. > 1)`,
expected: []string{
"D0, P[], (!!seq)::- 2\n",
"D0, P[], (!!seq)::- 3\n",
},
},
{
skipDoc: true,
description: "Filter array to empty",
document: `[1,2,3]`,
expression: `filter(. > 4)`,
expected: []string{
},
},
{
skipDoc: true,
description: "Filter empty array",
document: `[]`,
expression: `filter(. > 1)`,
expected: []string{
},
},
}

func TestFilterOperatorScenarios(t *testing.T) {
for _, tt := range filterOperatorScenarios {
testScenario(t, &tt)
}
documentOperatorScenarios(t, "filter", filterOperatorScenarios)
}