Golang influxql.Eval函數代碼示例

// Ensure an expression can be reduced.
func TestEval(t *testing.T) {
	for i, tt := range []struct {
		in   string
		out  interface{}
		data map[string]interface{}
	}{
		// Number literals.
		{in: `1 + 2`, out: float64(3)},
		{in: `(foo*2) + ( (4/2) + (3 * 5) - 0.5 )`, out: float64(26.5), data: map[string]interface{}{"foo": float64(5)}},
		{in: `foo / 2`, out: float64(2), data: map[string]interface{}{"foo": float64(4)}},
		{in: `4 = 4`, out: true},
		{in: `4 <> 4`, out: false},
		{in: `6 > 4`, out: true},
		{in: `4 >= 4`, out: true},
		{in: `4 < 6`, out: true},
		{in: `4 <= 4`, out: true},
		{in: `4 AND 5`, out: nil},

		// Boolean literals.
		{in: `true AND false`, out: false},
		{in: `true OR false`, out: true},

		// String literals.
		{in: `'foo' = 'bar'`, out: false},
		{in: `'foo' = 'foo'`, out: true},

		// Variable references.
		{in: `foo`, out: "bar", data: map[string]interface{}{"foo": "bar"}},
		{in: `foo = 'bar'`, out: true, data: map[string]interface{}{"foo": "bar"}},
		{in: `foo = 'bar'`, out: nil, data: map[string]interface{}{"foo": nil}},
		{in: `foo <> 'bar'`, out: true, data: map[string]interface{}{"foo": "xxx"}},
	} {
		// Evaluate expression.
		out := influxql.Eval(MustParseExpr(tt.in), tt.data)

		// Compare with expected output.
		if !reflect.DeepEqual(tt.out, out) {
			t.Errorf("%d. %s: unexpected output:\n\nexp=%#v\n\ngot=%#v\n\n", i, tt.in, tt.out, out)
			continue
		}
	}
}

func (c *seriesCursor) Next(fieldName string, fieldID uint8, tmin, tmax int64) (key int64, value interface{}) {
	// TODO: clean this up when we make it so series ids are only queried against the shards they exist in.
	//       Right now we query for all series ids on a query against each shard, even if that shard may not have the
	//       data, so cur could be nil.
	if c.cur == nil {
		return 0, nil
	}

	for {
		var k, v []byte
		if !c.initialized {
			k, v = c.cur.Seek(u64tob(uint64(tmin)))
			c.initialized = true
		} else {
			k, v = c.cur.Next()
		}

		// Exit if there is no more data.
		if k == nil {
			return 0, nil
		}

		// Marshal key & value.
		key, value = int64(btou64(k)), unmarshalValue(v, fieldID)

		if key > tmax {
			return 0, nil
		}

		// Evaluate condition. Move to next key/value if non-true.
		if c.condition != nil {
			if ok, _ := influxql.Eval(c.condition, map[string]interface{}{fieldName: value}).(bool); !ok {
				continue
			}
		}

		return key, value
	}
}

// matchesFilter returns true if the value matches the where clause
func matchesWhere(f influxql.Expr, fields map[string]interface{}) bool {
	if ok, _ := influxql.Eval(f, fields).(bool); !ok {
		return false
	}
	return true
}