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70 lines
1.3 KiB
Go
70 lines
1.3 KiB
Go
package parser
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import (
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"strings"
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)
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const (
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nullRep = "<null>"
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)
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// Node represents a node in the AST.
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type Node interface {
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// Pos returns the position of first character belonging to the node.
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Pos() Pos
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// End returns the position of first character immediately after the node.
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End() Pos
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// String returns a string representation of the node.
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String() string
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}
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// IdentList represents a list of identifiers.
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type IdentList struct {
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LParen Pos
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VarArgs bool
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List []*Ident
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RParen Pos
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}
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// Pos returns the position of first character belonging to the node.
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func (n *IdentList) Pos() Pos {
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if n.LParen.IsValid() {
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return n.LParen
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}
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if len(n.List) > 0 {
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return n.List[0].Pos()
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}
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return NoPos
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}
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// End returns the position of first character immediately after the node.
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func (n *IdentList) End() Pos {
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if n.RParen.IsValid() {
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return n.RParen + 1
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}
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if l := len(n.List); l > 0 {
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return n.List[l-1].End()
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}
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return NoPos
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}
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// NumFields returns the number of fields.
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func (n *IdentList) NumFields() int {
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if n == nil {
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return 0
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}
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return len(n.List)
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}
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func (n *IdentList) String() string {
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var list []string
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for i, e := range n.List {
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if n.VarArgs && i == len(n.List)-1 {
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list = append(list, "..."+e.String())
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} else {
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list = append(list, e.String())
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}
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}
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return "(" + strings.Join(list, ", ") + ")"
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}
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