debug for compilation flows

compiler/compiler.go

@@ -2,10 +2,12 @@ package compiler
 
 import (
 	"fmt"
+	"log"
 	"monkey/ast"
 	"monkey/code"
 	"monkey/object"
 	"sort"
+	"strings"
 )
 
 type EmittedInstruction struct {
@@ -20,6 +22,9 @@ type CompilationScope struct {
 }
 
 type Compiler struct {
+	Debug bool
+
+	l         int
 	constants []object.Object
 
 	symbolTable *SymbolTable
@@ -61,8 +66,16 @@ func NewWithState(s *SymbolTable, constants []object.Object) *Compiler {
 }
 
 func (c *Compiler) Compile(node ast.Node) error {
+	if c.Debug {
+		log.Printf(
+			"%s Compiling %T: %s\n",
+			strings.Repeat(" ", c.l), node, node.String(),
+		)
+	}
+
 	switch node := node.(type) {
 	case *ast.Program:
+		c.l++
 		for _, s := range node.Statements {
 			err := c.Compile(s)
 			if err != nil {
@@ -71,7 +84,9 @@ func (c *Compiler) Compile(node ast.Node) error {
 		}
 
 	case *ast.ExpressionStatement:
+		c.l++
 		err := c.Compile(node.Expression)
+		c.l--
 		if err != nil {
 			return err
 		}
@@ -82,12 +97,16 @@ func (c *Compiler) Compile(node ast.Node) error {
 
 	case *ast.InfixExpression:
 		if node.Operator == "<" || node.Operator == "<=" {
+			c.l++
 			err := c.Compile(node.Right)
+			c.l--
 			if err != nil {
 				return err
 			}
 
+			c.l++
 			err = c.Compile(node.Left)
+			c.l--
 			if err != nil {
 				return err
 			}
@@ -99,12 +118,16 @@ func (c *Compiler) Compile(node ast.Node) error {
 			return nil
 		}
 
+		c.l++
 		err := c.Compile(node.Left)
+		c.l--
 		if err != nil {
 			return err
 		}
 
+		c.l++
 		err = c.Compile(node.Right)
+		c.l--
 		if err != nil {
 			return err
 		}
@@ -142,7 +165,9 @@ func (c *Compiler) Compile(node ast.Node) error {
 		}
 
 	case *ast.PrefixExpression:
+		c.l++
 		err := c.Compile(node.Right)
+		c.l--
 		if err != nil {
 			return err
 		}
@@ -160,7 +185,9 @@ func (c *Compiler) Compile(node ast.Node) error {
 		if c.lastInstructionIs(code.OpPop) {
 			c.removeLastPop()
 		}
+		c.l++
 		err := c.Compile(node.Condition)
+		c.l--
 		if err != nil {
 			return err
 		}
@@ -168,7 +195,9 @@ func (c *Compiler) Compile(node ast.Node) error {
 		// Emit an `OpJumpNotTruthy` with a bogus value
 		jumpNotTruthyPos := c.emit(code.OpJumpNotTruthy, 9999)
 
+		c.l++
 		err = c.Compile(node.Consequence)
+		c.l--
 		if err != nil {
 			return err
 		}
@@ -186,7 +215,9 @@ func (c *Compiler) Compile(node ast.Node) error {
 		if node.Alternative == nil {
 			c.emit(code.OpNull)
 		} else {
-			err = c.Compile(node.Alternative)
+			c.l++
+			err := c.Compile(node.Alternative)
+			c.l--
 			if err != nil {
 				return err
 			}
@@ -200,12 +231,14 @@ func (c *Compiler) Compile(node ast.Node) error {
 		c.changeOperand(jumpPos, afterAlternativePos)
 
 	case *ast.BlockStatement:
+		c.l++
 		for _, s := range node.Statements {
 			err := c.Compile(s)
 			if err != nil {
 				return err
 			}
 		}
+		c.l--
 
 	case *ast.AssignmentStatement:
 		symbol, ok := c.symbolTable.Resolve(node.Name.Value)
@@ -213,7 +246,9 @@ func (c *Compiler) Compile(node ast.Node) error {
 			return fmt.Errorf("undefined variable %s", node.Value)
 		}
 
+		c.l++
 		err := c.Compile(node.Value)
+		c.l--
 		if err != nil {
 			return err
 		}
@@ -230,7 +265,9 @@ func (c *Compiler) Compile(node ast.Node) error {
 			symbol = c.symbolTable.Define(node.Name.Value)
 		}
 
+		c.l++
 		err := c.Compile(node.Value)
+		c.l--
 		if err != nil {
 			return err
 		}
@@ -255,7 +292,9 @@ func (c *Compiler) Compile(node ast.Node) error {
 
 	case *ast.ArrayLiteral:
 		for _, el := range node.Elements {
+			c.l++
 			err := c.Compile(el)
+			c.l--
 			if err != nil {
 				return err
 			}
@@ -273,11 +312,15 @@ func (c *Compiler) Compile(node ast.Node) error {
 		})
 
 		for _, k := range keys {
+			c.l++
 			err := c.Compile(k)
+			c.l--
 			if err != nil {
 				return err
 			}
+			c.l++
 			err = c.Compile(node.Pairs[k])
+			c.l--
 			if err != nil {
 				return err
 			}
@@ -286,12 +329,16 @@ func (c *Compiler) Compile(node ast.Node) error {
 		c.emit(code.OpHash, len(node.Pairs)*2)
 
 	case *ast.IndexExpression:
+		c.l++
 		err := c.Compile(node.Left)
+		c.l--
 		if err != nil {
 			return err
 		}
 
+		c.l++
 		err = c.Compile(node.Index)
+		c.l--
 		if err != nil {
 			return err
 		}
@@ -309,7 +356,9 @@ func (c *Compiler) Compile(node ast.Node) error {
 			c.symbolTable.Define(p.Value)
 		}
 
+		c.l++
 		err := c.Compile(node.Body)
+		c.l--
 		if err != nil {
 			return err
 		}
@@ -340,7 +389,9 @@ func (c *Compiler) Compile(node ast.Node) error {
 		c.emit(code.OpClosure, fnIndex, len(freeSymbols))
 
 	case *ast.ReturnStatement:
+		c.l++
 		err := c.Compile(node.ReturnValue)
+		c.l--
 		if err != nil {
 			return err
 		}
@@ -348,7 +399,9 @@ func (c *Compiler) Compile(node ast.Node) error {
 		c.emit(code.OpReturn)
 
 	case *ast.CallExpression:
+		c.l++
 		err := c.Compile(node.Function)
+		c.l--
 		if err != nil {
 			return err
 		}
@@ -365,7 +418,9 @@ func (c *Compiler) Compile(node ast.Node) error {
 	case *ast.WhileExpression:
 		jumpConditionPos := len(c.currentInstructions())
 
+		c.l++
 		err := c.Compile(node.Condition)
+		c.l--
 		if err != nil {
 			return err
 		}
@@ -373,10 +428,12 @@ func (c *Compiler) Compile(node ast.Node) error {
 		// Emit an `OpJump`with a bogus value
 		jumpIfFalsePos := c.emit(code.OpJumpNotTruthy, 0xFFFF)
 
+		c.l++
 		err = c.Compile(node.Consequence)
 		if err != nil {
 			return err
 		}
+		c.l--
 
 		c.emit(code.OpJump, jumpConditionPos)
 

repl/repl.go

@@ -116,6 +116,7 @@ func (r *REPL) Exec(f io.Reader) (state *VMState) {
 	}
 
 	c := compiler.NewWithState(state.symbols, state.constants)
+	c.Debug = r.opts.Debug
 	err = c.Compile(program)
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "Woops! Compilation failed:\n %s\n", err)
@@ -197,6 +198,7 @@ func (r *REPL) StartExecLoop(in io.Reader, out io.Writer, state *VMState) {
 		}
 
 		c := compiler.NewWithState(state.symbols, state.constants)
+		c.Debug = r.opts.Debug
 		err := c.Compile(program)
 		if err != nil {
 			fmt.Fprintf(os.Stderr, "Woops! Compilation failed:\n %s\n", err)