sq/libsq/ast/walker_test.go

package ast

import (
	"testing"

	"github.com/stretchr/testify/assert"

	"github.com/neilotoole/slogt"
)

func TestWalker(t *testing.T) {
	const q1 = `@mydb1 | .user  | join(.address, .user.uid == .address.uid) | .uid, .username, .country`

	p := getSLQParser(q1)
	query := p.Query()
	ast, err := buildAST(slogt.New(t), query)

	assert.Nil(t, err)
	assert.NotNil(t, ast)

	walker := NewWalker(ast)
	count := 0

	visitor := func(w *Walker, node Node) error {
		count++
		return w.visitChildren(node)
	}

	walker.AddVisitor(typeJoinNode, visitor)
	err = walker.Walk()
	assert.Nil(t, err)
	assert.Equal(t, 1, count)

	// test multiple visitors on the same node type
	walker = NewWalker(ast)
	countA := 0
	visitorA := func(w *Walker, node Node) error {
		countA++
		return w.visitChildren(node)
	}
	countB := 0
	visitorB := func(w *Walker, node Node) error {
		countB++
		return w.visitChildren(node)
	}

	walker.AddVisitor(typeTblSelectorNode, visitorA)
	walker.AddVisitor(typeColSelectorNode, visitorB)
	err = walker.Walk()
	assert.Nil(t, err)
	assert.Equal(t, 1, countA)
	assert.Equal(t, 3, countB)
}