From a5e44a7e070595d594b8c968062e9226e6cac2cf Mon Sep 17 00:00:00 2001
From: Ian Gulliver <git@flamingcow.io>
Date: Mon, 22 Nov 2021 20:33:22 -0800
Subject: [PATCH] Switch to add/remove instruction mutation

---
 gen/instruction.go      |  6 +++---
 gen/opcode.go           |  2 +-
 gen/operand.go          |  2 +-
 gen/program.go          | 19 -------------------
 grow/definition.go      | 12 ++++++++++--
 grow/defs/mul_five.yaml |  2 +-
 grow/mutate.go          | 36 ++++++++++++++++++++++++++++++++++++
 test/gen_test.go        |  9 ---------
 8 files changed, 52 insertions(+), 36 deletions(-)
 delete mode 100644 gen/program.go
 create mode 100644 grow/mutate.go
 delete mode 100644 test/gen_test.go

diff --git a/gen/instruction.go b/gen/instruction.go
index a98004d..58cf937 100644
--- a/gen/instruction.go
+++ b/gen/instruction.go
@@ -2,13 +2,13 @@ package gen
 
 import "github.com/firestuff/subcoding/vm"
 
-func randInstruction(prog *vm.Program) *vm.Instruction {
+func RandInstruction(prog *vm.Program) *vm.Instruction {
 	instr := &vm.Instruction{
-		OpCode: randOpCode(),
+		OpCode: RandOpCode(),
 	}
 
 	for i, t := range vm.OperandsByOpCode[instr.OpCode] {
-		instr.Operands[i] = randOperand(prog, t)
+		instr.Operands[i] = RandOperand(prog, t)
 	}
 
 	return instr
diff --git a/gen/opcode.go b/gen/opcode.go
index c82e2c7..95588aa 100644
--- a/gen/opcode.go
+++ b/gen/opcode.go
@@ -48,7 +48,7 @@ var opCodes = []vm.OpCodeType{
 	vm.OpSqrt,
 }
 
-func randOpCode() vm.OpCodeType {
+func RandOpCode() vm.OpCodeType {
 	// Uniform distribution
 	return opCodes[rand.Intn(len(opCodes))]
 }
diff --git a/gen/operand.go b/gen/operand.go
index 0599242..fbdff1e 100644
--- a/gen/operand.go
+++ b/gen/operand.go
@@ -4,7 +4,7 @@ import "math/rand"
 
 import "github.com/firestuff/subcoding/vm"
 
-func randOperand(prog *vm.Program, t vm.OperandNumericType) *vm.Operand {
+func RandOperand(prog *vm.Program, t vm.OperandNumericType) *vm.Operand {
 	for {
 		op := &vm.Operand{
 			Type: randOperandType(),
diff --git a/gen/program.go b/gen/program.go
deleted file mode 100644
index 3e3e8dd..0000000
--- a/gen/program.go
+++ /dev/null
@@ -1,19 +0,0 @@
-package gen
-
-import "github.com/firestuff/subcoding/vm"
-
-func RandProgram(globalMemorySize, functionMemorySize, instructionLimit uint64) *vm.Program {
-	prog := &vm.Program{
-		GlobalMemorySize:   globalMemorySize,
-		FunctionMemorySize: functionMemorySize,
-		InstructionLimit:   instructionLimit,
-	}
-
-	prog.Functions = append(prog.Functions, &vm.Function{
-		Instructions: []*vm.Instruction{
-			randInstruction(prog),
-		},
-	})
-
-	return prog
-}
diff --git a/grow/definition.go b/grow/definition.go
index 405648f..996e8b0 100644
--- a/grow/definition.go
+++ b/grow/definition.go
@@ -4,7 +4,6 @@ import "io"
 
 import "gopkg.in/yaml.v2"
 
-import "github.com/firestuff/subcoding/gen"
 import "github.com/firestuff/subcoding/vm"
 
 type Definition struct {
@@ -37,10 +36,19 @@ func (def *Definition) Grow(statusChan chan<- Status) (*vm.Program, error) {
 		statusChan <- status
 	}
 
+	prog := &vm.Program{
+		GlobalMemorySize:   def.GlobalMemorySize,
+		FunctionMemorySize: def.FunctionMemorySize,
+		InstructionLimit:   def.InstructionLimit,
+		Functions: []*vm.Function{
+			&vm.Function{},
+		},
+	}
+
 	for {
 		status.Attempts++
 
-		prog := gen.RandProgram(def.GlobalMemorySize, def.FunctionMemorySize, def.InstructionLimit)
+		Mutate(prog)
 
 		score, err := def.score(prog)
 		if err != nil {
diff --git a/grow/defs/mul_five.yaml b/grow/defs/mul_five.yaml
index bb97b0d..f57a77d 100644
--- a/grow/defs/mul_five.yaml
+++ b/grow/defs/mul_five.yaml
@@ -1,6 +1,6 @@
 global_memory_size: 1
 function_memory_size: 1
-instruction_limit: 2
+instruction_limit: 10
 samples:
 - in:  [0]
   out: [0]
diff --git a/grow/mutate.go b/grow/mutate.go
new file mode 100644
index 0000000..2a627c8
--- /dev/null
+++ b/grow/mutate.go
@@ -0,0 +1,36 @@
+package grow
+
+import "math"
+import "math/rand"
+
+import "github.com/firestuff/subcoding/gen"
+import "github.com/firestuff/subcoding/vm"
+
+func Mutate(prog *vm.Program) {
+	target := int(math.Max(2, rand.NormFloat64()*10+15))
+
+	if len(prog.Functions[0].Instructions) < target {
+		addInstruction(prog, prog.Functions[0])
+	} else {
+		removeInstruction(prog, prog.Functions[0])
+	}
+}
+
+func addInstruction(prog *vm.Program, fnc *vm.Function) {
+	if len(fnc.Instructions) == 0 {
+		fnc.Instructions = append(fnc.Instructions, gen.RandInstruction(prog))
+	} else {
+		i := rand.Intn(len(fnc.Instructions))
+		fnc.Instructions = append(fnc.Instructions[:i+1], fnc.Instructions[i:]...)
+		fnc.Instructions[i] = gen.RandInstruction(prog)
+	}
+}
+
+func removeInstruction(prog *vm.Program, fnc *vm.Function) {
+	if len(fnc.Instructions) == 0 {
+		return
+	}
+
+	i := rand.Intn(len(fnc.Instructions))
+	fnc.Instructions = append(fnc.Instructions[:i], fnc.Instructions[i+1:]...)
+}
diff --git a/test/gen_test.go b/test/gen_test.go
deleted file mode 100644
index 8f54e68..0000000
--- a/test/gen_test.go
+++ /dev/null
@@ -1,9 +0,0 @@
-package test
-
-import "testing"
-
-import "github.com/firestuff/subcoding/gen"
-
-func TestRandProgram(t *testing.T) {
-	gen.RandProgram(4, 4, 0)
-}