feat/schema: add parser

schema/errors/errors.go

@@ -0,0 +1,108 @@
+// Code generated by gocc; DO NOT EDIT.
+
+package errors
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+	"unicode"
+
+	"azalea/schema/token"
+)
+
+type ErrorSymbol interface {
+}
+
+type Error struct {
+	Err            error
+	ErrorToken     *token.Token
+	ErrorSymbols   []ErrorSymbol
+	ExpectedTokens []string
+	StackTop       int
+}
+
+func (e *Error) String() string {
+	w := new(strings.Builder)
+	if e.Err != nil {
+		fmt.Fprintln(w, "Error ", e.Err)
+	} else {
+		fmt.Fprintln(w, "Error")
+	}
+	fmt.Fprintf(w, "Token: type=%d, lit=%s\n", e.ErrorToken.Type, e.ErrorToken.Lit)
+	fmt.Fprintf(w, "Pos: offset=%d, line=%d, column=%d\n", e.ErrorToken.Pos.Offset, e.ErrorToken.Pos.Line, e.ErrorToken.Pos.Column)
+	fmt.Fprint(w, "Expected one of: ")
+	for _, sym := range e.ExpectedTokens {
+		fmt.Fprint(w, string(sym), " ")
+	}
+	fmt.Fprintln(w, "ErrorSymbol:")
+	for _, sym := range e.ErrorSymbols {
+		fmt.Fprintf(w, "%v\n", sym)
+	}
+
+	return w.String()
+}
+
+func DescribeExpected(tokens []string) string {
+	switch len(tokens) {
+	case 0:
+		return "unexpected additional tokens"
+
+	case 1:
+		return "expected " + tokens[0]
+
+	case 2:
+		return "expected either " + tokens[0] + " or " + tokens[1]
+
+	case 3:
+		// Oxford-comma rules require more than 3 items in a list for the
+		// comma to appear before the 'or'
+		return fmt.Sprintf("expected one of %s, %s or %s", tokens[0], tokens[1], tokens[2])
+
+	default:
+		// Oxford-comma separated alternatives list.
+		tokens = append(tokens[:len(tokens)-1], "or "+tokens[len(tokens)-1])
+		return "expected one of " + strings.Join(tokens, ", ")
+	}
+}
+
+func DescribeToken(tok *token.Token) string {
+	switch tok.Type {
+	case token.INVALID:
+		return fmt.Sprintf("unknown/invalid token %q", tok.Lit)
+	case token.EOF:
+		return "end-of-file"
+	default:
+		return fmt.Sprintf("%q", tok.Lit)
+	}
+}
+
+func (e *Error) Error() string {
+	// identify the line and column of the error in 'gnu' style so it can be understood
+	// by editors and IDEs; user will need to prefix it with a filename.
+	text := fmt.Sprintf("%d:%d: error: ", e.ErrorToken.Pos.Line, e.ErrorToken.Pos.Column)
+
+	// See if the error token can provide us with the filename.
+	switch src := e.ErrorToken.Pos.Context.(type) {
+	case token.Sourcer:
+		text = src.Source() + ":" + text
+	}
+
+	if e.Err != nil {
+		// Custom error specified, e.g. by << nil, errors.New("missing newline") >>
+		text += e.Err.Error()
+	} else {
+		tokens := make([]string, len(e.ExpectedTokens))
+		for idx, token := range e.ExpectedTokens {
+			if !unicode.IsLetter(rune(token[0])) {
+				token = strconv.Quote(token)
+			}
+			tokens[idx] = token
+		}
+		text += DescribeExpected(tokens)
+		actual := DescribeToken(e.ErrorToken)
+		text += fmt.Sprintf("; got: %s", actual)
+	}
+
+	return text
+}