Improved code readability.
Added IfExpressions, BlockStatements, and FunctionLiterals git-svn-id: https://svn.tlawal.org/svn/monkey@35 f6afcba9-9ef1-4bdd-9b72-7484f5705bac
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ast/ast.go
147
ast/ast.go
@ -3,6 +3,7 @@ package ast
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import (
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"bytes"
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"monkey/token"
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"strings"
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)
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type Node interface {
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@ -32,51 +33,13 @@ type Program struct {
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Statements []Statement
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}
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type Identifier struct {
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Token token.Token // the token.IDENT token
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Value string
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}
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// Let Statements
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type LetStatement struct {
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Token token.Token // token.LET token
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Name *Identifier
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Value Expression
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}
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type ReturnStatement struct {
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Token token.Token // token.RETURN token
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ReturnValue Expression
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}
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type ExpressionStatement struct {
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Token token.Token // the first token in the expression
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Expression Expression
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}
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type IntegerLiteral struct {
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Token token.Token
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Value int64
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}
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type PrefixExpression struct {
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Token token.Token // prefix token i.e. !
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Operator string
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Right Expression
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}
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type InfixExpression struct {
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Token token.Token // operator tokens i.e. +, -, *, /
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Left Expression
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Operator string
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Right Expression
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}
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type Boolean struct {
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Token token.Token
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Value bool
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}
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// Let Statements
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func (ls *LetStatement) statement_node() {}
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func (ls *LetStatement) TokenLiteral() string {
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@ -97,6 +60,11 @@ func (ls *LetStatement) String() string {
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}
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// Identifier
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type Identifier struct {
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Token token.Token // the token.IDENT token
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Value string
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}
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func (i *Identifier) expression_node() {}
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func (i *Identifier) TokenLiteral() string {
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@ -117,6 +85,11 @@ func (p *Program) TokenLiteral() string {
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}
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// Return Statements
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type ReturnStatement struct {
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Token token.Token // token.RETURN token
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ReturnValue Expression
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}
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func (rs *ReturnStatement) statement_node() {}
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func (rs *ReturnStatement) TokenLiteral() string {
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@ -134,6 +107,11 @@ func (rs *ReturnStatement) String() string {
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}
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// Expression Statement
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type ExpressionStatement struct {
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Token token.Token // the first token in the expression
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Expression Expression
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}
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func (es *ExpressionStatement) statement_node() {}
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func (es *ExpressionStatement) TokenLiteral() string {
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@ -148,6 +126,11 @@ func (es *ExpressionStatement) String() string {
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}
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// IntegerLiteral
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type IntegerLiteral struct {
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Token token.Token
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Value int64
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}
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func (il *IntegerLiteral) expression_node() {}
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func (il *IntegerLiteral) TokenLiteral() string {
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@ -159,6 +142,12 @@ func (il *IntegerLiteral) String() string {
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}
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// PrefixExpression
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type PrefixExpression struct {
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Token token.Token // prefix token i.e. !
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Operator string
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Right Expression
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}
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func (pe *PrefixExpression) expression_node() {}
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func (pe *PrefixExpression) TokenLiteral() string {
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return pe.Token.Literal
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@ -175,6 +164,13 @@ func (pe *PrefixExpression) String() string {
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}
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// Infix Expression
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type InfixExpression struct {
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Token token.Token // operator tokens i.e. +, -, *, /
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Left Expression
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Operator string
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Right Expression
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}
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func (ie *InfixExpression) expression_node() {}
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func (ie *InfixExpression) TokenLiteral() string { return ie.Token.Literal }
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func (ie *InfixExpression) String() string {
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@ -189,6 +185,79 @@ func (ie *InfixExpression) String() string {
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}
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// Booleans
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type Boolean struct {
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Token token.Token
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Value bool
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}
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func (b *Boolean) expression_node() {}
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func (b *Boolean) TokenLiteral() string { return b.Token.Literal }
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func (b *Boolean) String() string { return b.Token.Literal }
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// If Expression
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type IfExpression struct {
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Token token.Token // the 'if' token
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Condition Expression
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Consequence *BlockStatement
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Alternative *BlockStatement
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}
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func (ie *IfExpression) expression_node() {}
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func (ie *IfExpression) TokenLiteral() string { return ie.Token.Literal }
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func (ie *IfExpression) String() string {
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var out bytes.Buffer
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out.WriteString("if")
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out.WriteString(ie.Condition.String())
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out.WriteString(" ")
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out.WriteString(ie.Consequence.String())
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if ie.Alternative != nil {
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out.WriteString("else")
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out.WriteString(ie.Alternative.String())
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}
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return out.String()
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}
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// Block Statements
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type BlockStatement struct {
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Token token.Token // the { token
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Statements []Statement
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}
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func (bs *BlockStatement) statement_node() {}
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func (bs *BlockStatement) TokenLiteral() string {
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return bs.Token.Literal
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}
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func (bs *BlockStatement) String() string {
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var out bytes.Buffer
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for _, s := range bs.Statements {
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out.WriteString(s.String())
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}
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return out.String()
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}
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// Function literals
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type FunctionLiteral struct {
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Token token.Token // the 'fn' token
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Parameters []*Identifier
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Body *BlockStatement
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}
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func (fl *FunctionLiteral) expression_node() {}
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func (fl *FunctionLiteral) TokenLiteral() string { return fl.Token.Literal }
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func (fl *FunctionLiteral) String() string {
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var out bytes.Buffer
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params := []string{}
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for _, p := range fl.Parameters{
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params = append(params, p.String())
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}
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out.WriteString(fl.TokenLiteral())
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out.WriteString("(")
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out.WriteString(strings.Join(params, ", "))
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out.WriteString(") ")
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out.WriteString(fl.Body.String())
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return out.String()
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}
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