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// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Parse nodes.
package parse
import (
"bytes"
"fmt"
"os"
"strconv"
"strings"
)
// A node is an element in the parse tree. The interface is trivial.
type Node interface {
Type() NodeType
String() string
}
// NodeType identifies the type of a parse tree node.
type NodeType int
// Type returns itself and provides an easy default implementation
// for embedding in a Node. Embedded in all non-trivial Nodes.
func (t NodeType) Type() NodeType {
return t
}
const (
NodeText NodeType = iota // Plain text.
NodeAction // A simple action such as field evaluation.
NodeBool // A boolean constant.
NodeCommand // An element of a pipeline.
NodeDot // The cursor, dot.
nodeElse // An else action. Not added to tree.
nodeEnd // An end action. Not added to tree.
NodeField // A field or method name.
NodeIdentifier // An identifier; always a function name.
NodeIf // An if action.
NodeList // A list of Nodes.
NodeNumber // A numerical constant.
NodePipe // A pipeline of commands.
NodeRange // A range action.
NodeString // A string constant.
NodeTemplate // A template invocation action.
NodeVariable // A $ variable.
NodeWith // A with action.
)
// Nodes.
// ListNode holds a sequence of nodes.
type ListNode struct {
NodeType
Nodes []Node // The element nodes in lexical order.
}
func newList() *ListNode {
return &ListNode{NodeType: NodeList}
}
func (l *ListNode) append(n Node) {
l.Nodes = append(l.Nodes, n)
}
func (l *ListNode) String() string {
b := new(bytes.Buffer)
fmt.Fprint(b, "[")
for _, n := range l.Nodes {
fmt.Fprint(b, n)
}
fmt.Fprint(b, "]")
return b.String()
}
// TextNode holds plain text.
type TextNode struct {
NodeType
Text []byte // The text; may span newlines.
}
func newText(text string) *TextNode {
return &TextNode{NodeType: NodeText, Text: []byte(text)}
}
func (t *TextNode) String() string {
return fmt.Sprintf("(text: %q)", t.Text)
}
// PipeNode holds a pipeline with optional declaration
type PipeNode struct {
NodeType
Line int // The line number in the input.
Decl []*VariableNode // Variable declarations in lexical order.
Cmds []*CommandNode // The commands in lexical order.
}
func newPipeline(line int, decl []*VariableNode) *PipeNode {
return &PipeNode{NodeType: NodePipe, Line: line, Decl: decl}
}
func (p *PipeNode) append(command *CommandNode) {
p.Cmds = append(p.Cmds, command)
}
func (p *PipeNode) String() string {
if p.Decl != nil {
return fmt.Sprintf("%v := %v", p.Decl, p.Cmds)
}
return fmt.Sprintf("%v", p.Cmds)
}
// ActionNode holds an action (something bounded by delimiters).
// Control actions have their own nodes; ActionNode represents simple
// ones such as field evaluations.
type ActionNode struct {
NodeType
Line int // The line number in the input.
Pipe *PipeNode // The pipeline in the action.
}
func newAction(line int, pipe *PipeNode) *ActionNode {
return &ActionNode{NodeType: NodeAction, Line: line, Pipe: pipe}
}
func (a *ActionNode) String() string {
return fmt.Sprintf("(action: %v)", a.Pipe)
}
// CommandNode holds a command (a pipeline inside an evaluating action).
type CommandNode struct {
NodeType
Args []Node // Arguments in lexical order: Identifier, field, or constant.
}
func newCommand() *CommandNode {
return &CommandNode{NodeType: NodeCommand}
}
func (c *CommandNode) append(arg Node) {
c.Args = append(c.Args, arg)
}
func (c *CommandNode) String() string {
return fmt.Sprintf("(command: %v)", c.Args)
}
// IdentifierNode holds an identifier.
type IdentifierNode struct {
NodeType
Ident string // The identifier's name.
}
// NewIdentifier returns a new IdentifierNode with the given identifier name.
func NewIdentifier(ident string) *IdentifierNode {
return &IdentifierNode{NodeType: NodeIdentifier, Ident: ident}
}
func (i *IdentifierNode) String() string {
return fmt.Sprintf("I=%s", i.Ident)
}
// VariableNode holds a list of variable names. The dollar sign is
// part of the name.
type VariableNode struct {
NodeType
Ident []string // Variable names in lexical order.
}
func newVariable(ident string) *VariableNode {
return &VariableNode{NodeType: NodeVariable, Ident: strings.Split(ident, ".")}
}
func (v *VariableNode) String() string {
return fmt.Sprintf("V=%s", v.Ident)
}
// DotNode holds the special identifier '.'. It is represented by a nil pointer.
type DotNode bool
func newDot() *DotNode {
return nil
}
func (d *DotNode) Type() NodeType {
return NodeDot
}
func (d *DotNode) String() string {
return "{{<.>}}"
}
// FieldNode holds a field (identifier starting with '.').
// The names may be chained ('.x.y').
// The period is dropped from each ident.
type FieldNode struct {
NodeType
Ident []string // The identifiers in lexical order.
}
func newField(ident string) *FieldNode {
return &FieldNode{NodeType: NodeField, Ident: strings.Split(ident[1:], ".")} // [1:] to drop leading period
}
func (f *FieldNode) String() string {
return fmt.Sprintf("F=%s", f.Ident)
}
// BoolNode holds a boolean constant.
type BoolNode struct {
NodeType
True bool // The value of the boolean constant.
}
func newBool(true bool) *BoolNode {
return &BoolNode{NodeType: NodeBool, True: true}
}
func (b *BoolNode) String() string {
return fmt.Sprintf("B=%t", b.True)
}
// NumberNode holds a number: signed or unsigned integer, float, or complex.
// The value is parsed and stored under all the types that can represent the value.
// This simulates in a small amount of code the behavior of Go's ideal constants.
type NumberNode struct {
NodeType
IsInt bool // Number has an integral value.
IsUint bool // Number has an unsigned integral value.
IsFloat bool // Number has a floating-point value.
IsComplex bool // Number is complex.
Int64 int64 // The signed integer value.
Uint64 uint64 // The unsigned integer value.
Float64 float64 // The floating-point value.
Complex128 complex128 // The complex value.
Text string // The original textual representation from the input.
}
func newNumber(text string, typ itemType) (*NumberNode, os.Error) {
n := &NumberNode{NodeType: NodeNumber, Text: text}
switch typ {
case itemCharConstant:
rune, _, tail, err := strconv.UnquoteChar(text[1:], text[0])
if err != nil {
return nil, err
}
if tail != "'" {
return nil, fmt.Errorf("malformed character constant: %s", text)
}
n.Int64 = int64(rune)
n.IsInt = true
n.Uint64 = uint64(rune)
n.IsUint = true
n.Float64 = float64(rune) // odd but those are the rules.
n.IsFloat = true
return n, nil
case itemComplex:
// fmt.Sscan can parse the pair, so let it do the work.
if _, err := fmt.Sscan(text, &n.Complex128); err != nil {
return nil, err
}
n.IsComplex = true
n.simplifyComplex()
return n, nil
}
// Imaginary constants can only be complex unless they are zero.
if len(text) > 0 && text[len(text)-1] == 'i' {
f, err := strconv.Atof64(text[:len(text)-1])
if err == nil {
n.IsComplex = true
n.Complex128 = complex(0, f)
n.simplifyComplex()
return n, nil
}
}
// Do integer test first so we get 0x123 etc.
u, err := strconv.Btoui64(text, 0) // will fail for -0; fixed below.
if err == nil {
n.IsUint = true
n.Uint64 = u
}
i, err := strconv.Btoi64(text, 0)
if err == nil {
n.IsInt = true
n.Int64 = i
if i == 0 {
n.IsUint = true // in case of -0.
n.Uint64 = u
}
}
// If an integer extraction succeeded, promote the float.
if n.IsInt {
n.IsFloat = true
n.Float64 = float64(n.Int64)
} else if n.IsUint {
n.IsFloat = true
n.Float64 = float64(n.Uint64)
} else {
f, err := strconv.Atof64(text)
if err == nil {
n.IsFloat = true
n.Float64 = f
// If a floating-point extraction succeeded, extract the int if needed.
if !n.IsInt && float64(int64(f)) == f {
n.IsInt = true
n.Int64 = int64(f)
}
if !n.IsUint && float64(uint64(f)) == f {
n.IsUint = true
n.Uint64 = uint64(f)
}
}
}
if !n.IsInt && !n.IsUint && !n.IsFloat {
return nil, fmt.Errorf("illegal number syntax: %q", text)
}
return n, nil
}
// simplifyComplex pulls out any other types that are represented by the complex number.
// These all require that the imaginary part be zero.
func (n *NumberNode) simplifyComplex() {
n.IsFloat = imag(n.Complex128) == 0
if n.IsFloat {
n.Float64 = real(n.Complex128)
n.IsInt = float64(int64(n.Float64)) == n.Float64
if n.IsInt {
n.Int64 = int64(n.Float64)
}
n.IsUint = float64(uint64(n.Float64)) == n.Float64
if n.IsUint {
n.Uint64 = uint64(n.Float64)
}
}
}
func (n *NumberNode) String() string {
return fmt.Sprintf("N=%s", n.Text)
}
// StringNode holds a string constant. The value has been "unquoted".
type StringNode struct {
NodeType
Quoted string // The original text of the string, with quotes.
Text string // The string, after quote processing.
}
func newString(orig, text string) *StringNode {
return &StringNode{NodeType: NodeString, Quoted: orig, Text: text}
}
func (s *StringNode) String() string {
return fmt.Sprintf("S=%#q", s.Text)
}
// endNode represents an {{end}} action. It is represented by a nil pointer.
// It does not appear in the final parse tree.
type endNode bool
func newEnd() *endNode {
return nil
}
func (e *endNode) Type() NodeType {
return nodeEnd
}
func (e *endNode) String() string {
return "{{end}}"
}
// elseNode represents an {{else}} action. Does not appear in the final tree.
type elseNode struct {
NodeType
Line int // The line number in the input.
}
func newElse(line int) *elseNode {
return &elseNode{NodeType: nodeElse, Line: line}
}
func (e *elseNode) Type() NodeType {
return nodeElse
}
func (e *elseNode) String() string {
return "{{else}}"
}
// IfNode represents an {{if}} action and its commands.
type IfNode struct {
NodeType
Line int // The line number in the input.
Pipe *PipeNode // The pipeline to be evaluated.
List *ListNode // What to execute if the value is non-empty.
ElseList *ListNode // What to execute if the value is empty (nil if absent).
}
func newIf(line int, pipe *PipeNode, list, elseList *ListNode) *IfNode {
return &IfNode{NodeType: NodeIf, Line: line, Pipe: pipe, List: list, ElseList: elseList}
}
func (i *IfNode) String() string {
if i.ElseList != nil {
return fmt.Sprintf("({{if %s}} %s {{else}} %s)", i.Pipe, i.List, i.ElseList)
}
return fmt.Sprintf("({{if %s}} %s)", i.Pipe, i.List)
}
// RangeNode represents a {{range}} action and its commands.
type RangeNode struct {
NodeType
Line int // The line number in the input.
Pipe *PipeNode // The pipeline to be evaluated.
List *ListNode // What to execute if the value is non-empty.
ElseList *ListNode // What to execute if the value is empty (nil if absent).
}
func newRange(line int, pipe *PipeNode, list, elseList *ListNode) *RangeNode {
return &RangeNode{NodeType: NodeRange, Line: line, Pipe: pipe, List: list, ElseList: elseList}
}
func (r *RangeNode) String() string {
if r.ElseList != nil {
return fmt.Sprintf("({{range %s}} %s {{else}} %s)", r.Pipe, r.List, r.ElseList)
}
return fmt.Sprintf("({{range %s}} %s)", r.Pipe, r.List)
}
// TemplateNode represents a {{template}} action.
type TemplateNode struct {
NodeType
Line int // The line number in the input.
Name string // The name of the template (unquoted).
Pipe *PipeNode // The command to evaluate as dot for the template.
}
func newTemplate(line int, name string, pipe *PipeNode) *TemplateNode {
return &TemplateNode{NodeType: NodeTemplate, Line: line, Name: name, Pipe: pipe}
}
func (t *TemplateNode) String() string {
if t.Pipe == nil {
return fmt.Sprintf("{{template %q}}", t.Name)
}
return fmt.Sprintf("{{template %q %s}}", t.Name, t.Pipe)
}
// WithNode represents a {{with}} action and its commands.
type WithNode struct {
NodeType
Line int // The line number in the input.
Pipe *PipeNode // The pipeline to be evaluated.
List *ListNode // What to execute if the value is non-empty.
ElseList *ListNode // What to execute if the value is empty (nil if absent).
}
func newWith(line int, pipe *PipeNode, list, elseList *ListNode) *WithNode {
return &WithNode{NodeType: NodeWith, Line: line, Pipe: pipe, List: list, ElseList: elseList}
}
func (w *WithNode) String() string {
if w.ElseList != nil {
return fmt.Sprintf("({{with %s}} %s {{else}} %s)", w.Pipe, w.List, w.ElseList)
}
return fmt.Sprintf("({{with %s}} %s)", w.Pipe, w.List)
}