618 lines
14 KiB
Go
618 lines
14 KiB
Go
package influxql
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import (
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"bufio"
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"bytes"
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"errors"
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"fmt"
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"io"
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)
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// Scanner represents a lexical scanner for InfluxQL.
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type Scanner struct {
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r *reader
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}
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// NewScanner returns a new instance of Scanner.
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func NewScanner(r io.Reader) *Scanner {
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return &Scanner{r: &reader{r: bufio.NewReader(r)}}
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}
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// Scan returns the next token and position from the underlying reader.
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// Also returns the literal text read for strings, numbers, and duration tokens
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// since these token types can have different literal representations.
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func (s *Scanner) Scan() (tok Token, pos Pos, lit string) {
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// Read next code point.
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ch0, pos := s.r.read()
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// If we see whitespace then consume all contiguous whitespace.
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// If we see a letter, or certain acceptable special characters, then consume
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// as an ident or reserved word.
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if isWhitespace(ch0) {
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return s.scanWhitespace()
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} else if isLetter(ch0) || ch0 == '_' {
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s.r.unread()
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return s.scanIdent(true)
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} else if isDigit(ch0) {
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return s.scanNumber()
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}
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// Otherwise parse individual characters.
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switch ch0 {
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case eof:
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return EOF, pos, ""
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case '"':
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s.r.unread()
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return s.scanIdent(true)
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case '\'':
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return s.scanString()
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case '.':
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ch1, _ := s.r.read()
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s.r.unread()
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if isDigit(ch1) {
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return s.scanNumber()
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}
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return DOT, pos, ""
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case '$':
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tok, _, lit = s.scanIdent(false)
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if tok != IDENT {
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return tok, pos, "$" + lit
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}
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return BOUNDPARAM, pos, "$" + lit
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case '+':
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return ADD, pos, ""
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case '-':
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ch1, _ := s.r.read()
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if ch1 == '-' {
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s.skipUntilNewline()
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return COMMENT, pos, ""
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}
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s.r.unread()
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return SUB, pos, ""
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case '*':
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return MUL, pos, ""
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case '/':
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ch1, _ := s.r.read()
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if ch1 == '*' {
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if err := s.skipUntilEndComment(); err != nil {
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return ILLEGAL, pos, ""
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}
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return COMMENT, pos, ""
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} else {
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s.r.unread()
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}
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return DIV, pos, ""
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case '%':
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return MOD, pos, ""
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case '&':
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return BITWISE_AND, pos, ""
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case '|':
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return BITWISE_OR, pos, ""
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case '^':
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return BITWISE_XOR, pos, ""
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case '=':
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if ch1, _ := s.r.read(); ch1 == '~' {
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return EQREGEX, pos, ""
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}
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s.r.unread()
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return EQ, pos, ""
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case '!':
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if ch1, _ := s.r.read(); ch1 == '=' {
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return NEQ, pos, ""
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} else if ch1 == '~' {
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return NEQREGEX, pos, ""
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}
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s.r.unread()
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case '>':
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if ch1, _ := s.r.read(); ch1 == '=' {
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return GTE, pos, ""
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}
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s.r.unread()
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return GT, pos, ""
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case '<':
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if ch1, _ := s.r.read(); ch1 == '=' {
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return LTE, pos, ""
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} else if ch1 == '>' {
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return NEQ, pos, ""
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}
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s.r.unread()
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return LT, pos, ""
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case '(':
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return LPAREN, pos, ""
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case ')':
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return RPAREN, pos, ""
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case ',':
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return COMMA, pos, ""
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case ';':
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return SEMICOLON, pos, ""
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case ':':
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if ch1, _ := s.r.read(); ch1 == ':' {
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return DOUBLECOLON, pos, ""
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}
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s.r.unread()
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return COLON, pos, ""
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}
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return ILLEGAL, pos, string(ch0)
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}
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// scanWhitespace consumes the current rune and all contiguous whitespace.
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func (s *Scanner) scanWhitespace() (tok Token, pos Pos, lit string) {
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// Create a buffer and read the current character into it.
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var buf bytes.Buffer
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ch, pos := s.r.curr()
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_, _ = buf.WriteRune(ch)
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// Read every subsequent whitespace character into the buffer.
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// Non-whitespace characters and EOF will cause the loop to exit.
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for {
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ch, _ = s.r.read()
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if ch == eof {
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break
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} else if !isWhitespace(ch) {
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s.r.unread()
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break
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} else {
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_, _ = buf.WriteRune(ch)
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}
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}
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return WS, pos, buf.String()
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}
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// skipUntilNewline skips characters until it reaches a newline.
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func (s *Scanner) skipUntilNewline() {
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for {
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if ch, _ := s.r.read(); ch == '\n' || ch == eof {
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return
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}
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}
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}
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// skipUntilEndComment skips characters until it reaches a '*/' symbol.
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func (s *Scanner) skipUntilEndComment() error {
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for {
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if ch1, _ := s.r.read(); ch1 == '*' {
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// We might be at the end.
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star:
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ch2, _ := s.r.read()
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if ch2 == '/' {
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return nil
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} else if ch2 == '*' {
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// We are back in the state machine since we see a star.
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goto star
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} else if ch2 == eof {
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return io.EOF
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}
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} else if ch1 == eof {
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return io.EOF
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}
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}
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}
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func (s *Scanner) scanIdent(lookup bool) (tok Token, pos Pos, lit string) {
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// Save the starting position of the identifier.
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_, pos = s.r.read()
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s.r.unread()
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var buf bytes.Buffer
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for {
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if ch, _ := s.r.read(); ch == eof {
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break
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} else if ch == '"' {
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tok0, pos0, lit0 := s.scanString()
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if tok0 == BADSTRING || tok0 == BADESCAPE {
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return tok0, pos0, lit0
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}
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return IDENT, pos, lit0
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} else if isIdentChar(ch) {
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s.r.unread()
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buf.WriteString(ScanBareIdent(s.r))
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} else {
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s.r.unread()
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break
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}
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}
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lit = buf.String()
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// If the literal matches a keyword then return that keyword.
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if lookup {
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if tok = Lookup(lit); tok != IDENT {
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return tok, pos, ""
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}
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}
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return IDENT, pos, lit
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}
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// scanString consumes a contiguous string of non-quote characters.
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// Quote characters can be consumed if they're first escaped with a backslash.
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func (s *Scanner) scanString() (tok Token, pos Pos, lit string) {
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s.r.unread()
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_, pos = s.r.curr()
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var err error
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lit, err = ScanString(s.r)
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if err == errBadString {
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return BADSTRING, pos, lit
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} else if err == errBadEscape {
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_, pos = s.r.curr()
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return BADESCAPE, pos, lit
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}
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return STRING, pos, lit
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}
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// ScanRegex consumes a token to find escapes
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func (s *Scanner) ScanRegex() (tok Token, pos Pos, lit string) {
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_, pos = s.r.curr()
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// Start & end sentinels.
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start, end := '/', '/'
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// Valid escape chars.
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escapes := map[rune]rune{'/': '/'}
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b, err := ScanDelimited(s.r, start, end, escapes, true)
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if err == errBadEscape {
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_, pos = s.r.curr()
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return BADESCAPE, pos, lit
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} else if err != nil {
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return BADREGEX, pos, lit
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}
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return REGEX, pos, string(b)
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}
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// scanNumber consumes anything that looks like the start of a number.
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func (s *Scanner) scanNumber() (tok Token, pos Pos, lit string) {
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var buf bytes.Buffer
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// Check if the initial rune is a ".".
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ch, pos := s.r.curr()
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if ch == '.' {
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// Peek and see if the next rune is a digit.
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ch1, _ := s.r.read()
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s.r.unread()
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if !isDigit(ch1) {
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return ILLEGAL, pos, "."
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}
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// Unread the full stop so we can read it later.
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s.r.unread()
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} else {
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s.r.unread()
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}
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// Read as many digits as possible.
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_, _ = buf.WriteString(s.scanDigits())
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// If next code points are a full stop and digit then consume them.
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isDecimal := false
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if ch0, _ := s.r.read(); ch0 == '.' {
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isDecimal = true
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if ch1, _ := s.r.read(); isDigit(ch1) {
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_, _ = buf.WriteRune(ch0)
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_, _ = buf.WriteRune(ch1)
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_, _ = buf.WriteString(s.scanDigits())
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} else {
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s.r.unread()
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}
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} else {
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s.r.unread()
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}
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// Read as a duration or integer if it doesn't have a fractional part.
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if !isDecimal {
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// If the next rune is a letter then this is a duration token.
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if ch0, _ := s.r.read(); isLetter(ch0) || ch0 == 'µ' {
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_, _ = buf.WriteRune(ch0)
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for {
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ch1, _ := s.r.read()
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if !isLetter(ch1) && ch1 != 'µ' {
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s.r.unread()
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break
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}
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_, _ = buf.WriteRune(ch1)
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}
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// Continue reading digits and letters as part of this token.
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for {
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if ch0, _ := s.r.read(); isLetter(ch0) || ch0 == 'µ' || isDigit(ch0) {
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_, _ = buf.WriteRune(ch0)
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} else {
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s.r.unread()
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break
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}
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}
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return DURATIONVAL, pos, buf.String()
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} else {
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s.r.unread()
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return INTEGER, pos, buf.String()
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}
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}
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return NUMBER, pos, buf.String()
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}
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// scanDigits consumes a contiguous series of digits.
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func (s *Scanner) scanDigits() string {
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var buf bytes.Buffer
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for {
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ch, _ := s.r.read()
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if !isDigit(ch) {
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s.r.unread()
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break
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}
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_, _ = buf.WriteRune(ch)
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}
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return buf.String()
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}
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// isWhitespace returns true if the rune is a space, tab, or newline.
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func isWhitespace(ch rune) bool { return ch == ' ' || ch == '\t' || ch == '\n' }
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// isLetter returns true if the rune is a letter.
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func isLetter(ch rune) bool { return (ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z') }
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// isDigit returns true if the rune is a digit.
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func isDigit(ch rune) bool { return (ch >= '0' && ch <= '9') }
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// isIdentChar returns true if the rune can be used in an unquoted identifier.
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func isIdentChar(ch rune) bool { return isLetter(ch) || isDigit(ch) || ch == '_' }
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// isIdentFirstChar returns true if the rune can be used as the first char in an unquoted identifer.
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func isIdentFirstChar(ch rune) bool { return isLetter(ch) || ch == '_' }
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// bufScanner represents a wrapper for scanner to add a buffer.
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// It provides a fixed-length circular buffer that can be unread.
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type bufScanner struct {
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s *Scanner
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i int // buffer index
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n int // buffer size
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buf [3]struct {
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tok Token
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pos Pos
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lit string
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}
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}
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// newBufScanner returns a new buffered scanner for a reader.
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func newBufScanner(r io.Reader) *bufScanner {
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return &bufScanner{s: NewScanner(r)}
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}
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// Scan reads the next token from the scanner.
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func (s *bufScanner) Scan() (tok Token, pos Pos, lit string) {
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return s.scanFunc(s.s.Scan)
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}
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// ScanRegex reads a regex token from the scanner.
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func (s *bufScanner) ScanRegex() (tok Token, pos Pos, lit string) {
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return s.scanFunc(s.s.ScanRegex)
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}
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// scanFunc uses the provided function to scan the next token.
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func (s *bufScanner) scanFunc(scan func() (Token, Pos, string)) (tok Token, pos Pos, lit string) {
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// If we have unread tokens then read them off the buffer first.
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if s.n > 0 {
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s.n--
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return s.curr()
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}
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// Move buffer position forward and save the token.
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s.i = (s.i + 1) % len(s.buf)
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buf := &s.buf[s.i]
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buf.tok, buf.pos, buf.lit = scan()
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return s.curr()
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}
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// Unscan pushes the previously token back onto the buffer.
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func (s *bufScanner) Unscan() { s.n++ }
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// curr returns the last read token.
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func (s *bufScanner) curr() (tok Token, pos Pos, lit string) {
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buf := &s.buf[(s.i-s.n+len(s.buf))%len(s.buf)]
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return buf.tok, buf.pos, buf.lit
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}
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// reader represents a buffered rune reader used by the scanner.
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// It provides a fixed-length circular buffer that can be unread.
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type reader struct {
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r io.RuneScanner
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i int // buffer index
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n int // buffer char count
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pos Pos // last read rune position
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buf [3]struct {
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ch rune
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pos Pos
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}
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eof bool // true if reader has ever seen eof.
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}
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// ReadRune reads the next rune from the reader.
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// This is a wrapper function to implement the io.RuneReader interface.
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// Note that this function does not return size.
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func (r *reader) ReadRune() (ch rune, size int, err error) {
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ch, _ = r.read()
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if ch == eof {
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err = io.EOF
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}
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return
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}
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// UnreadRune pushes the previously read rune back onto the buffer.
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// This is a wrapper function to implement the io.RuneScanner interface.
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func (r *reader) UnreadRune() error {
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r.unread()
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return nil
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}
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// read reads the next rune from the reader.
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func (r *reader) read() (ch rune, pos Pos) {
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// If we have unread characters then read them off the buffer first.
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if r.n > 0 {
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r.n--
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return r.curr()
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}
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// Read next rune from underlying reader.
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// Any error (including io.EOF) should return as EOF.
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ch, _, err := r.r.ReadRune()
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if err != nil {
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ch = eof
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} else if ch == '\r' {
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if ch, _, err := r.r.ReadRune(); err != nil {
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// nop
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} else if ch != '\n' {
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_ = r.r.UnreadRune()
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}
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ch = '\n'
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}
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// Save character and position to the buffer.
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r.i = (r.i + 1) % len(r.buf)
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buf := &r.buf[r.i]
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buf.ch, buf.pos = ch, r.pos
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// Update position.
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// Only count EOF once.
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if ch == '\n' {
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r.pos.Line++
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r.pos.Char = 0
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} else if !r.eof {
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r.pos.Char++
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}
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// Mark the reader as EOF.
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// This is used so we don't double count EOF characters.
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if ch == eof {
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r.eof = true
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}
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return r.curr()
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}
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// unread pushes the previously read rune back onto the buffer.
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func (r *reader) unread() {
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r.n++
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}
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// curr returns the last read character and position.
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func (r *reader) curr() (ch rune, pos Pos) {
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i := (r.i - r.n + len(r.buf)) % len(r.buf)
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buf := &r.buf[i]
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return buf.ch, buf.pos
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}
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// eof is a marker code point to signify that the reader can't read any more.
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const eof = rune(0)
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// ScanDelimited reads a delimited set of runes
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func ScanDelimited(r io.RuneScanner, start, end rune, escapes map[rune]rune, escapesPassThru bool) ([]byte, error) {
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// Scan start delimiter.
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if ch, _, err := r.ReadRune(); err != nil {
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return nil, err
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} else if ch != start {
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return nil, fmt.Errorf("expected %s; found %s", string(start), string(ch))
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}
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var buf bytes.Buffer
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for {
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ch0, _, err := r.ReadRune()
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if ch0 == end {
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return buf.Bytes(), nil
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} else if err != nil {
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return buf.Bytes(), err
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} else if ch0 == '\n' {
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return nil, errors.New("delimited text contains new line")
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} else if ch0 == '\\' {
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// If the next character is an escape then write the escaped char.
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// If it's not a valid escape then return an error.
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ch1, _, err := r.ReadRune()
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if err != nil {
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return nil, err
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}
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c, ok := escapes[ch1]
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if !ok {
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if escapesPassThru {
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// Unread ch1 (char after the \)
|
|
_ = r.UnreadRune()
|
|
// Write ch0 (\) to the output buffer.
|
|
_, _ = buf.WriteRune(ch0)
|
|
continue
|
|
} else {
|
|
buf.Reset()
|
|
_, _ = buf.WriteRune(ch0)
|
|
_, _ = buf.WriteRune(ch1)
|
|
return buf.Bytes(), errBadEscape
|
|
}
|
|
}
|
|
|
|
_, _ = buf.WriteRune(c)
|
|
} else {
|
|
_, _ = buf.WriteRune(ch0)
|
|
}
|
|
}
|
|
}
|
|
|
|
// ScanString reads a quoted string from a rune reader.
|
|
func ScanString(r io.RuneScanner) (string, error) {
|
|
ending, _, err := r.ReadRune()
|
|
if err != nil {
|
|
return "", errBadString
|
|
}
|
|
|
|
var buf bytes.Buffer
|
|
for {
|
|
ch0, _, err := r.ReadRune()
|
|
if ch0 == ending {
|
|
return buf.String(), nil
|
|
} else if err != nil || ch0 == '\n' {
|
|
return buf.String(), errBadString
|
|
} else if ch0 == '\\' {
|
|
// If the next character is an escape then write the escaped char.
|
|
// If it's not a valid escape then return an error.
|
|
ch1, _, _ := r.ReadRune()
|
|
if ch1 == 'n' {
|
|
_, _ = buf.WriteRune('\n')
|
|
} else if ch1 == '\\' {
|
|
_, _ = buf.WriteRune('\\')
|
|
} else if ch1 == '"' {
|
|
_, _ = buf.WriteRune('"')
|
|
} else if ch1 == '\'' {
|
|
_, _ = buf.WriteRune('\'')
|
|
} else {
|
|
return string(ch0) + string(ch1), errBadEscape
|
|
}
|
|
} else {
|
|
_, _ = buf.WriteRune(ch0)
|
|
}
|
|
}
|
|
}
|
|
|
|
var errBadString = errors.New("bad string")
|
|
var errBadEscape = errors.New("bad escape")
|
|
|
|
// ScanBareIdent reads bare identifier from a rune reader.
|
|
func ScanBareIdent(r io.RuneScanner) string {
|
|
// Read every ident character into the buffer.
|
|
// Non-ident characters and EOF will cause the loop to exit.
|
|
var buf bytes.Buffer
|
|
for {
|
|
ch, _, err := r.ReadRune()
|
|
if err != nil {
|
|
break
|
|
} else if !isIdentChar(ch) {
|
|
r.UnreadRune()
|
|
break
|
|
} else {
|
|
_, _ = buf.WriteRune(ch)
|
|
}
|
|
}
|
|
return buf.String()
|
|
}
|
|
|
|
// IsRegexOp returns true if the operator accepts a regex operand.
|
|
func IsRegexOp(t Token) bool {
|
|
return (t == EQREGEX || t == NEQREGEX)
|
|
}
|