Update to tengo v2 (#976)

vendor/github.com/d5/tengo/v2/instructions.go

@@ -0,0 +1,61 @@
+package tengo
+
+import (
+	"fmt"
+
+	"github.com/d5/tengo/v2/parser"
+)
+
+// MakeInstruction returns a bytecode for an opcode and the operands.
+func MakeInstruction(opcode parser.Opcode, operands ...int) []byte {
+	numOperands := parser.OpcodeOperands[opcode]
+
+	totalLen := 1
+	for _, w := range numOperands {
+		totalLen += w
+	}
+
+	instruction := make([]byte, totalLen)
+	instruction[0] = opcode
+
+	offset := 1
+	for i, o := range operands {
+		width := numOperands[i]
+		switch width {
+		case 1:
+			instruction[offset] = byte(o)
+		case 2:
+			n := uint16(o)
+			instruction[offset] = byte(n >> 8)
+			instruction[offset+1] = byte(n)
+		}
+		offset += width
+	}
+	return instruction
+}
+
+// FormatInstructions returns string representation of bytecode instructions.
+func FormatInstructions(b []byte, posOffset int) []string {
+	var out []string
+
+	i := 0
+	for i < len(b) {
+		numOperands := parser.OpcodeOperands[b[i]]
+		operands, read := parser.ReadOperands(numOperands, b[i+1:])
+
+		switch len(numOperands) {
+		case 0:
+			out = append(out, fmt.Sprintf("%04d %-7s",
+				posOffset+i, parser.OpcodeNames[b[i]]))
+		case 1:
+			out = append(out, fmt.Sprintf("%04d %-7s %-5d",
+				posOffset+i, parser.OpcodeNames[b[i]], operands[0]))
+		case 2:
+			out = append(out, fmt.Sprintf("%04d %-7s %-5d %-5d",
+				posOffset+i, parser.OpcodeNames[b[i]],
+				operands[0], operands[1]))
+		}
+		i += 1 + read
+	}
+	return out
+}