Add new SQL parser to support S3 Select syntax (#7102)

- New parser written from scratch, allows easier and complete parsing
  of the full S3 Select SQL syntax. Parser definition is directly
  provided by the AST defined for the SQL grammar.

- Bring support to parse and interpret SQL involving JSON path
  expressions; evaluation of JSON path expressions will be
  subsequently added.

- Bring automatic type inference and conversion for untyped
  values (e.g. CSV data).

vendor/github.com/alecthomas/participle/lexer/peek.go

@@ -0,0 +1,37 @@
+package lexer
+
+// Upgrade a Lexer to a PeekingLexer with arbitrary lookahead.
+func Upgrade(lexer Lexer) PeekingLexer {
+	if peeking, ok := lexer.(PeekingLexer); ok {
+		return peeking
+	}
+	return &lookaheadLexer{Lexer: lexer}
+}
+
+type lookaheadLexer struct {
+	Lexer
+	peeked []Token
+}
+
+func (l *lookaheadLexer) Peek(n int) (Token, error) {
+	for len(l.peeked) <= n {
+		t, err := l.Lexer.Next()
+		if err != nil {
+			return Token{}, err
+		}
+		if t.EOF() {
+			return t, nil
+		}
+		l.peeked = append(l.peeked, t)
+	}
+	return l.peeked[n], nil
+}
+
+func (l *lookaheadLexer) Next() (Token, error) {
+	if len(l.peeked) > 0 {
+		t := l.peeked[0]
+		l.peeked = l.peeked[1:]
+		return t, nil
+	}
+	return l.Lexer.Next()
+}