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@@ -8,6 +8,10 @@ type Parser struct {
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// be set before use.
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Lexer Lexer
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// TokenNames assigns names to token kinds. This should be set before
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// use.
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TokenNames map[TokenKind] string
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// Token is the current token the parser is operating on.
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Token Token
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}
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@@ -17,8 +21,8 @@ type Parser struct {
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func (this *Parser) Expect (allowed ...TokenKind) error {
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if !this.Token.Is(allowed...) {
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return Errorf (
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this.Token.Position, "unexpected %v; expected %s",
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this.Token, commaList(allowed...))
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this.Token.Position, "unexpected %s; expected %s",
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this.tokenName(this.Token.Kind), commaList(this.tokenNames(allowed...)...))
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}
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return nil
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}
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@@ -29,8 +33,8 @@ func (this *Parser) Expect (allowed ...TokenKind) error {
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func (this *Parser) ExpectDesc (description string, allowed ...TokenKind) error {
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if !this.Token.Is(allowed...) {
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return Errorf (
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this.Token.Position, "unexpected %v; expected %s",
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this.Token, description)
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this.Token.Position, "unexpected %s; expected %s",
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this.tokenName(this.Token.Kind), description)
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}
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return nil
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}
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@@ -54,8 +58,8 @@ func (this *Parser) ExpectNextDesc (description string, allowed ...TokenKind) er
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func (this *Parser) ExpectValue (kind TokenKind, allowed ...string) error {
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if !((this.Token.Is(kind) || kind == 0) && this.Token.ValueIs(allowed...)) {
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return Errorf (
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this.Token.Position, "unexpected %v; expected %s",
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this.Token, commaList(allowed))
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this.Token.Position, "unexpected %s; expected %s",
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this.tokenName(this.Token.Kind), commaList(allowed))
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}
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return nil
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}
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@@ -65,8 +69,8 @@ func (this *Parser) ExpectValue (kind TokenKind, allowed ...string) error {
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func (this *Parser) ExpectValueDesc (description string, kind TokenKind, allowed ...string) error {
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if !this.Token.Is(kind) || !this.Token.ValueIs(allowed...) {
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return Errorf (
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this.Token.Position, "unexpected %v; expected %s",
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this.Token, description)
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this.Token.Position, "unexpected %s; expected %s",
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this.tokenName(this.Token.Kind), description)
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}
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return nil
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}
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@@ -110,6 +114,23 @@ func (this *Parser) EOF () bool {
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return this.Token.EOF()
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}
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func (this *Parser) tokenName (kind TokenKind) string {
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if this.TokenNames != nil {
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if name, ok := this.TokenNames[kind]; ok {
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return name
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}
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}
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return fmt.Sprintf("TokenKind(%d)", kind)
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}
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func (this *Parser) tokenNames (kinds ...TokenKind) []string {
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names := make([]string, len(kinds))
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for index, kind := range kinds {
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names[index] = this.tokenName(kind)
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}
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return names
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}
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func commaList[ELEMENT any] (items ...ELEMENT) string {
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list := ""
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