interp: Make has/1 work for _ext keys

pkg/interp/testdata/value.fqtest

@@ -28,3 +28,128 @@ $ fq -d mp3 '.headers[0][]' /test.mp3
 0x20|30 30 00                                       |00.             |
     |00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f|0123456789abcdef|
 0x20|         00 00 00 00 00 00 00 00 00 00         |   ..........   |.headers[0].padding: Correct (none) (zero padding)
+# TODO: proper buffer_root test
+$ fq -d mp3 -i . /test.mp3
+mp3> . | (root, buffer_root, format_root, parent | ._path | path_to_expr), [parents | ._path | path_to_expr]
+"."
+"."
+"."
+"."
+[]
+mp3> .frames[0].side_info.granules[1] | (root, buffer_root, format_root, parent | ._path | path_to_expr), [parents | ._path | path_to_expr]
+"."
+"."
+".frames[0]"
+".frames[0].side_info.granules"
+[
+  ".frames[0].side_info.granules",
+  ".frames[0].side_info",
+  ".frames[0]",
+  ".frames",
+  "."
+]
+mp3> 123 | root
+error: expected a decode value but got: number (123)
+mp3> 123 | buffer_root
+error: expected a decode value but got: number (123)
+mp3> 123 | format_root
+error: expected a decode value but got: number (123)
+mp3> 123 | parent
+error: expected a decode value but got: number (123)
+mp3> 123 | parents
+error: expected a decode value but got: number (123)
+mp3> ^D
+$ fq -d mp3 -i . /test.mp3
+mp3> has("_start")
+true
+mp3> has("_stop")
+true
+mp3> has("_len")
+true
+mp3> has("_name")
+true
+mp3> has("_root")
+true
+mp3> has("_buffer_root")
+true
+mp3> has("_format_root")
+true
+mp3> has("_parent")
+true
+mp3> has("_symbol")
+true
+mp3> has("_description")
+true
+mp3> has("_path")
+true
+mp3> has("_bits")
+true
+mp3> has("_bytes")
+true
+mp3> has("_error")
+true
+mp3> has("_unknown")
+true
+mp3> has("_format")
+true
+mp3> has("_abc")
+error: expected a extkey but got: _abc
+mp3> ^D
+$ fq -d mp3 -i . /test.mp3
+mp3> ._start
+0
+mp3> ._stop
+5152
+mp3> ._len
+5152
+mp3> ._name
+""
+mp3> ._root
+     |00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f|0123456789abcdef|.: {} /test.mp3 (mp3)
+0x000|49 44 33 04 00 00 00 00 00 23 54 53 53 45 00 00|ID3......#TSSE..|  headers: [1]
+*    |until 0x2c.7 (45)                              |                |
+0x020|                                       ff fb 40|             ..@|  frames: [3]
+0x030|c0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00|................|
+*    |until 0x283.7 (end) (599)                      |                |
+     |                                               |                |  footers: [0]
+mp3> ._buffer_root
+     |00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f|0123456789abcdef|.: {} /test.mp3 (mp3)
+0x000|49 44 33 04 00 00 00 00 00 23 54 53 53 45 00 00|ID3......#TSSE..|  headers: [1]
+*    |until 0x2c.7 (45)                              |                |
+0x020|                                       ff fb 40|             ..@|  frames: [3]
+0x030|c0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00|................|
+*    |until 0x283.7 (end) (599)                      |                |
+     |                                               |                |  footers: [0]
+mp3> ._format_root
+     |00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f|0123456789abcdef|.: {} /test.mp3 (mp3)
+0x000|49 44 33 04 00 00 00 00 00 23 54 53 53 45 00 00|ID3......#TSSE..|  headers: [1]
+*    |until 0x2c.7 (45)                              |                |
+0x020|                                       ff fb 40|             ..@|  frames: [3]
+0x030|c0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00|................|
+*    |until 0x283.7 (end) (599)                      |                |
+     |                                               |                |  footers: [0]
+mp3> ._parent
+null
+mp3> ._symbol
+""
+mp3> ._description
+"/test.mp3"
+mp3> ._path
+[]
+mp3> ._bits
+     |00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f|0123456789abcdef|
+0x000|49 44 33 04 00 00 00 00 00 23 54 53 53 45 00 00|ID3......#TSSE..|.: none (5152 bits)
+*    |until 0x283.7 (end) (644)                      |                |
+mp3> ._bytes
+     |00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f|0123456789abcdef|
+0x000|49 44 33 04 00 00 00 00 00 23 54 53 53 45 00 00|ID3......#TSSE..|.: none (644 bytes)
+*    |until 0x283.7 (end) (644)                      |                |
+mp3> ._error
+null
+mp3> ._unknown
+false
+mp3> ._format
+"mp3"
+mp3> ._abc
+error: expected a extkey but got: _abc
+mp3> ^D

pkg/interp/value.go

@@ -38,12 +38,22 @@ type valueIf interface {
 	ToBuffer
 }
 
-func valueUnderscoreKey(name string, a, b func(name string) interface{}) interface{} {
+func valueKey(name string, a, b func(name string) interface{}) interface{} {
 	if strings.HasPrefix(name, "_") {
 		return a(name)
 	}
 	return b(name)
 }
+func valueHas(key interface{}, a func(name string) interface{}, b func(key interface{}) interface{}) interface{} {
+	stringKey, ok := key.(string)
+	if ok && strings.HasPrefix(stringKey, "_") {
+		if err, ok := a(stringKey).(error); ok {
+			return err
+		}
+		return true
+	}
+	return b(key)
+}
 
 func makeDecodeValue(dv *decode.Value) valueIf {
 	switch vv := dv.V.(type) {
@@ -211,7 +221,10 @@ type decodeValue struct {
 }
 
 func (v decodeValue) JQValueKey(name string) interface{} {
-	return valueUnderscoreKey(name, v.decodeValueBase.JQValueKey, v.JQValue.JQValueKey)
+	return valueKey(name, v.decodeValueBase.JQValueKey, v.JQValue.JQValueKey)
+}
+func (v decodeValue) JQValueHas(key interface{}) interface{} {
+	return valueHas(key, v.decodeValueBase.JQValueKey, v.JQValue.JQValueHas)
 }
 
 // string (*bitio.Buffer)
@@ -233,9 +246,11 @@ func NewStringBufferValueObject(dv *decode.Value, bb *bitio.Buffer) BufferDecode
 }
 
 func (v BufferDecodeValue) JQValueKey(name string) interface{} {
-	return valueUnderscoreKey(name, v.decodeValueBase.JQValueKey, v.Base.JQValueKey)
+	return valueKey(name, v.decodeValueBase.JQValueKey, v.Base.JQValueKey)
+}
+func (v BufferDecodeValue) JQValueHas(key interface{}) interface{} {
+	return valueHas(key, v.decodeValueBase.JQValueKey, v.Base.JQValueHas)
 }
-
 func (v BufferDecodeValue) JQValueLength() interface{} {
 	return int(v.Buffer.Len()) / 8
 }
@@ -302,7 +317,7 @@ func NewArrayDecodeValue(dv *decode.Value, a decode.Array) ArrayDecodeValue {
 }
 
 func (v ArrayDecodeValue) JQValueKey(name string) interface{} {
-	return valueUnderscoreKey(name, v.decodeValueBase.JQValueKey, v.Base.JQValueKey)
+	return valueKey(name, v.decodeValueBase.JQValueKey, v.Base.JQValueKey)
 }
 func (v ArrayDecodeValue) JQValueSliceLen() interface{} { return len(v.Array) }
 func (v ArrayDecodeValue) JQValueLength() interface{}   { return len(v.Array) }
@@ -338,11 +353,16 @@ func (v ArrayDecodeValue) JQValueKeys() interface{} {
 	return vs
 }
 func (v ArrayDecodeValue) JQValueHas(key interface{}) interface{} {
-	intKey, ok := key.(int)
+	return valueHas(
-	if !ok {
+		key,
-		return gojqextra.HasKeyTypeError{L: "array", R: fmt.Sprintf("%v", key)}
+		v.decodeValueBase.JQValueKey,
-	}
+		func(key interface{}) interface{} {
-	return intKey >= 0 && intKey < len(v.Array)
+			intKey, ok := key.(int)
+			if !ok {
+				return gojqextra.HasKeyTypeError{L: "array", R: fmt.Sprintf("%v", key)}
+			}
+			return intKey >= 0 && intKey < len(v.Array)
+		})
 }
 func (v ArrayDecodeValue) JQValueToGoJQ() interface{} {
 	vs := make([]interface{}, len(v.Array))
@@ -402,16 +422,22 @@ func (v StructDecodeValue) JQValueKeys() interface{} {
 	return vs
 }
 func (v StructDecodeValue) JQValueHas(key interface{}) interface{} {
-	stringKey, ok := key.(string)
+	return valueHas(
-	if !ok {
+		key,
-		return gojqextra.HasKeyTypeError{L: "object", R: fmt.Sprintf("%v", key)}
+		v.decodeValueBase.JQValueKey,
-	}
+		func(key interface{}) interface{} {
-	for _, f := range v.Struct {
+			stringKey, ok := key.(string)
-		if f.Name == stringKey {
+			if !ok {
-			return true
+				return gojqextra.HasKeyTypeError{L: "object", R: fmt.Sprintf("%v", key)}
-		}
+			}
-	}
+			for _, f := range v.Struct {
-	return false
+				if f.Name == stringKey {
+					return true
+				}
+			}
+			return false
+		},
+	)
 }
 func (v StructDecodeValue) JQValueToGoJQ() interface{} {
 	vm := make(map[string]interface{}, len(v.Struct))