Checking in vendor folder for ease of using go get.

vendor/github.com/pelletier/go-toml/query/parser.go

@@ -0,0 +1,275 @@
+/*
+  Based on the "jsonpath" spec/concept.
+
+  http://goessner.net/articles/JsonPath/
+  https://code.google.com/p/json-path/
+*/
+
+package query
+
+import (
+	"fmt"
+)
+
+const maxInt = int(^uint(0) >> 1)
+
+type queryParser struct {
+	flow         chan token
+	tokensBuffer []token
+	query        *Query
+	union        []pathFn
+	err          error
+}
+
+type queryParserStateFn func() queryParserStateFn
+
+// Formats and panics an error message based on a token
+func (p *queryParser) parseError(tok *token, msg string, args ...interface{}) queryParserStateFn {
+	p.err = fmt.Errorf(tok.Position.String()+": "+msg, args...)
+	return nil // trigger parse to end
+}
+
+func (p *queryParser) run() {
+	for state := p.parseStart; state != nil; {
+		state = state()
+	}
+}
+
+func (p *queryParser) backup(tok *token) {
+	p.tokensBuffer = append(p.tokensBuffer, *tok)
+}
+
+func (p *queryParser) peek() *token {
+	if len(p.tokensBuffer) != 0 {
+		return &(p.tokensBuffer[0])
+	}
+
+	tok, ok := <-p.flow
+	if !ok {
+		return nil
+	}
+	p.backup(&tok)
+	return &tok
+}
+
+func (p *queryParser) lookahead(types ...tokenType) bool {
+	result := true
+	buffer := []token{}
+
+	for _, typ := range types {
+		tok := p.getToken()
+		if tok == nil {
+			result = false
+			break
+		}
+		buffer = append(buffer, *tok)
+		if tok.typ != typ {
+			result = false
+			break
+		}
+	}
+	// add the tokens back to the buffer, and return
+	p.tokensBuffer = append(p.tokensBuffer, buffer...)
+	return result
+}
+
+func (p *queryParser) getToken() *token {
+	if len(p.tokensBuffer) != 0 {
+		tok := p.tokensBuffer[0]
+		p.tokensBuffer = p.tokensBuffer[1:]
+		return &tok
+	}
+	tok, ok := <-p.flow
+	if !ok {
+		return nil
+	}
+	return &tok
+}
+
+func (p *queryParser) parseStart() queryParserStateFn {
+	tok := p.getToken()
+
+	if tok == nil || tok.typ == tokenEOF {
+		return nil
+	}
+
+	if tok.typ != tokenDollar {
+		return p.parseError(tok, "Expected '$' at start of expression")
+	}
+
+	return p.parseMatchExpr
+}
+
+// handle '.' prefix, '[]', and '..'
+func (p *queryParser) parseMatchExpr() queryParserStateFn {
+	tok := p.getToken()
+	switch tok.typ {
+	case tokenDotDot:
+		p.query.appendPath(&matchRecursiveFn{})
+		// nested parse for '..'
+		tok := p.getToken()
+		switch tok.typ {
+		case tokenKey:
+			p.query.appendPath(newMatchKeyFn(tok.val))
+			return p.parseMatchExpr
+		case tokenLeftBracket:
+			return p.parseBracketExpr
+		case tokenStar:
+			// do nothing - the recursive predicate is enough
+			return p.parseMatchExpr
+		}
+
+	case tokenDot:
+		// nested parse for '.'
+		tok := p.getToken()
+		switch tok.typ {
+		case tokenKey:
+			p.query.appendPath(newMatchKeyFn(tok.val))
+			return p.parseMatchExpr
+		case tokenStar:
+			p.query.appendPath(&matchAnyFn{})
+			return p.parseMatchExpr
+		}
+
+	case tokenLeftBracket:
+		return p.parseBracketExpr
+
+	case tokenEOF:
+		return nil // allow EOF at this stage
+	}
+	return p.parseError(tok, "expected match expression")
+}
+
+func (p *queryParser) parseBracketExpr() queryParserStateFn {
+	if p.lookahead(tokenInteger, tokenColon) {
+		return p.parseSliceExpr
+	}
+	if p.peek().typ == tokenColon {
+		return p.parseSliceExpr
+	}
+	return p.parseUnionExpr
+}
+
+func (p *queryParser) parseUnionExpr() queryParserStateFn {
+	var tok *token
+
+	// this state can be traversed after some sub-expressions
+	// so be careful when setting up state in the parser
+	if p.union == nil {
+		p.union = []pathFn{}
+	}
+
+loop: // labeled loop for easy breaking
+	for {
+		if len(p.union) > 0 {
+			// parse delimiter or terminator
+			tok = p.getToken()
+			switch tok.typ {
+			case tokenComma:
+				// do nothing
+			case tokenRightBracket:
+				break loop
+			default:
+				return p.parseError(tok, "expected ',' or ']', not '%s'", tok.val)
+			}
+		}
+
+		// parse sub expression
+		tok = p.getToken()
+		switch tok.typ {
+		case tokenInteger:
+			p.union = append(p.union, newMatchIndexFn(tok.Int()))
+		case tokenKey:
+			p.union = append(p.union, newMatchKeyFn(tok.val))
+		case tokenString:
+			p.union = append(p.union, newMatchKeyFn(tok.val))
+		case tokenQuestion:
+			return p.parseFilterExpr
+		default:
+			return p.parseError(tok, "expected union sub expression, not '%s', %d", tok.val, len(p.union))
+		}
+	}
+
+	// if there is only one sub-expression, use that instead
+	if len(p.union) == 1 {
+		p.query.appendPath(p.union[0])
+	} else {
+		p.query.appendPath(&matchUnionFn{p.union})
+	}
+
+	p.union = nil // clear out state
+	return p.parseMatchExpr
+}
+
+func (p *queryParser) parseSliceExpr() queryParserStateFn {
+	// init slice to grab all elements
+	start, end, step := 0, maxInt, 1
+
+	// parse optional start
+	tok := p.getToken()
+	if tok.typ == tokenInteger {
+		start = tok.Int()
+		tok = p.getToken()
+	}
+	if tok.typ != tokenColon {
+		return p.parseError(tok, "expected ':'")
+	}
+
+	// parse optional end
+	tok = p.getToken()
+	if tok.typ == tokenInteger {
+		end = tok.Int()
+		tok = p.getToken()
+	}
+	if tok.typ == tokenRightBracket {
+		p.query.appendPath(newMatchSliceFn(start, end, step))
+		return p.parseMatchExpr
+	}
+	if tok.typ != tokenColon {
+		return p.parseError(tok, "expected ']' or ':'")
+	}
+
+	// parse optional step
+	tok = p.getToken()
+	if tok.typ == tokenInteger {
+		step = tok.Int()
+		if step < 0 {
+			return p.parseError(tok, "step must be a positive value")
+		}
+		tok = p.getToken()
+	}
+	if tok.typ != tokenRightBracket {
+		return p.parseError(tok, "expected ']'")
+	}
+
+	p.query.appendPath(newMatchSliceFn(start, end, step))
+	return p.parseMatchExpr
+}
+
+func (p *queryParser) parseFilterExpr() queryParserStateFn {
+	tok := p.getToken()
+	if tok.typ != tokenLeftParen {
+		return p.parseError(tok, "expected left-parenthesis for filter expression")
+	}
+	tok = p.getToken()
+	if tok.typ != tokenKey && tok.typ != tokenString {
+		return p.parseError(tok, "expected key or string for filter function name")
+	}
+	name := tok.val
+	tok = p.getToken()
+	if tok.typ != tokenRightParen {
+		return p.parseError(tok, "expected right-parenthesis for filter expression")
+	}
+	p.union = append(p.union, newMatchFilterFn(name, tok.Position))
+	return p.parseUnionExpr
+}
+
+func parseQuery(flow chan token) (*Query, error) {
+	parser := &queryParser{
+		flow:         flow,
+		tokensBuffer: []token{},
+		query:        newQuery(),
+	}
+	parser.run()
+	return parser.query, parser.err
+}