cleanup and error printing

cmd/sqv/main.go

@@ -11,12 +11,11 @@ import (
 )
 
 func main() {
-	s := `
-	CREATE TABLE TEST(
-		ID text PRIMARY KEY
-	);
+	s := `CREATE TABLE TEST(
+	ID text PRIMARY KEY
+);
 
-	CREATE TABLE sessions (
+CREATE TABLE sessions (
   session_id text PRIMARY KEY,
   access_token text NOT NULL,
   user_email text NOT NULL,

sql/lexer.go

@@ -28,6 +28,8 @@ const (
 	REFERENCES
 	KEY
 	NOT
+	IF
+	EXISTS
 
 	TEXT
 	INTEGER

sql/parser.go

@@ -1,7 +1,6 @@
 package sql
 
 import (
-	"errors"
 	"fmt"
 	"io"
 	"slices"
@@ -23,17 +22,13 @@ func NewParser(r io.Reader) *Parser {
 func (p *Parser) Parse() (*CreateTableStatement, error) {
 	tok, ok := p.expectOne(CREATE, EOF)
 	if !ok {
-		return nil, p.unexpectedToken()
+		return nil, p.unexpectedToken(CREATE, EOF)
 	} else if tok == EOF {
 		return nil, io.EOF
 	}
 
-	if !p.expectNext(TABLE) {
-		return nil, errors.New("Expect TABLE token")
-	}
-
-	if !p.expectNext(IDENT) {
-		return nil, errors.New("Expect IDENT token")
+	if !p.expectSequence(TABLE, IDENT) {
+		return nil, p.unexpectedToken()
 	}
 
 	stmt := CreateTableStatement{
@@ -41,9 +36,9 @@ func (p *Parser) Parse() (*CreateTableStatement, error) {
 		Columns:   make([]Column, 0),
 	}
 
-	_, tok, _ = p.scan()
-	if tok != LPAREN {
-		return nil, errors.New("Expect LPAREN token")
+	
+	if !p.expectNext(LPAREN) {
+		return nil, p.unexpectedToken(LPAREN)
 	}
 
 	for {
@@ -60,35 +55,24 @@ func (p *Parser) Parse() (*CreateTableStatement, error) {
 
 		case RPAREN:
 			if !p.expectNext(SEMI) {
-				return nil, p.unexpectedToken()
+				return nil, p.unexpectedToken(SEMI)
 			}
 			return &stmt, nil
 
 		case SEMI:
 			if lastTok != RPAREN {
-				return nil, p.unexpectedToken()
+				return nil, p.unexpectedToken(RPAREN)
 			}
 
 			return &stmt, nil
 
 		case FOREIGN:
-			if !p.expectNext(KEY) {
-				return nil, p.unexpectedToken()
-			}
-			if !p.expectNext(LPAREN) {
-				return nil, p.unexpectedToken()
-			}
-
-			if !p.expectNext(IDENT) {
+			if !p.expectSequence(KEY, LPAREN, IDENT) {
 				return nil, p.unexpectedToken()
 			}
 			columnName := p.last.lit
 
-			if !p.expectNext(RPAREN) {
-				return nil, p.unexpectedToken()
-			}
-
-			if !p.expectNext(REFERENCES) {
+			if !p.expectSequence(RPAREN, REFERENCES) {
 				return nil, p.unexpectedToken()
 			}
 
@@ -104,7 +88,7 @@ func (p *Parser) Parse() (*CreateTableStatement, error) {
 			stmt.Columns[column].Extra = append(stmt.Columns[column].Extra, ref)
 
 		default:
-			return nil, p.unexpectedToken()
+			return nil, p.unexpectedToken(IDENT, RPAREN, SEMI, FOREIGN)
 		}
 	}
 }
@@ -119,7 +103,7 @@ func (p *Parser) parseColumn() (Column, error) {
 	case INTEGER:
 		column.Type = lit
 	default:
-		return Column{}, p.unexpectedToken()
+		return Column{}, p.unexpectedToken(TEXT, INTEGER)
 	}
 
 	for {
@@ -134,7 +118,7 @@ func (p *Parser) parseColumn() (Column, error) {
 			fallthrough
 		case NOT:
 			if _, ok := p.expectOne(NULL, KEY); !ok {
-				return Column{}, p.unexpectedToken()
+				return Column{}, p.unexpectedToken(NULL, KEY)
 			}
 			column.Extra = append(column.Extra, fmt.Sprintf("%v_%v", lit, p.last.lit))
 
@@ -146,38 +130,63 @@ func (p *Parser) parseColumn() (Column, error) {
 			column.Extra = append(column.Extra, ref)
 
 		default:
-			return Column{}, p.unexpectedToken()
+			return Column{}, p.unexpectedToken(COMMA, RPAREN, PRIMARY, NOT, REFERENCES)
 		}
 	}
 }
 
-func (p *Parser) unexpectedToken() error {
-	return fmt.Errorf("Encountered unexpected token: %v lit: '%v' on pos: %v", p.last.tok, p.last.lit, p.last.pos)
+func (p *Parser) unexpectedToken(expected ...Token) error {
+	l := len(expected)
+	if l <= 0 {
+		return fmt.Errorf("Encountered unexpected token: %v lit: '%v' on pos: %v", p.last.tok, p.last.lit, p.last.pos)
+	} else if l == 1 {
+		return fmt.Errorf(
+			"Encountered unexpected token: %v lit: '%v' on pos: %v, expected %v",
+			p.last.tok,
+			p.last.lit,
+			p.last.pos,
+			expected[0],
+		)
+	} else {
+		return fmt.Errorf(
+			"Encountered unexpected token: %v lit: '%v' on pos: %v, expected one of '%v'",
+			p.last.tok,
+			p.last.lit,
+			p.last.pos,
+			arrayToString(expected, ", "),
+		)
+	}
 }
 
 func (p *Parser) references() (string, error) {
 	if !p.expectNext(IDENT) {
-		return "", p.unexpectedToken()
+		return "", p.unexpectedToken(IDENT)
 	}
 	referenceTableName := p.last.lit
 
-	if !p.expectNext(LPAREN) {
-		return "", p.unexpectedToken()
-	}
-
-	if !p.expectNext(IDENT) {
+	if !p.expectSequence(LPAREN, IDENT) {
 		return "", p.unexpectedToken()
 	}
 
 	referenceColumnName := p.last.lit
 
 	if !p.expectNext(RPAREN) {
-		return "", p.unexpectedToken()
+		return "", p.unexpectedToken(RPAREN)
 	}
 
 	return fmt.Sprintf("ref %v.%v", referenceTableName, referenceColumnName), nil
 }
 
+func (p *Parser) expectSequence(token ...Token) bool {
+	for _, tok := range token {
+		if !p.expectNext(tok) {
+			return false
+		}
+	}
+
+	return true
+}
+
 func (p *Parser) expectNext(token Token) bool {
 	_, tok, _ := p.scan()
 	return tok == token

sql/util.go

@@ -0,0 +1,13 @@
+package sql
+
+import (
+	"fmt"
+	"strings"
+)
+
+
+func arrayToString(a []Token, delim string) string {
+    return strings.Trim(strings.Replace(fmt.Sprint(a), " ", delim, -1), "[]")
+    //return strings.Trim(strings.Join(strings.Split(fmt.Sprint(a), " "), delim), "[]")
+    //return strings.Trim(strings.Join(strings.Fields(fmt.Sprint(a)), delim), "[]")
+}