chore: upgrade coredns version (#550)

vendor/github.com/expr-lang/expr/parser/parser.go

@@ -0,0 +1,891 @@
+package parser
+
+import (
+	"fmt"
+	"math"
+	"strconv"
+	"strings"
+
+	. "github.com/expr-lang/expr/ast"
+	"github.com/expr-lang/expr/builtin"
+	"github.com/expr-lang/expr/conf"
+	"github.com/expr-lang/expr/file"
+	. "github.com/expr-lang/expr/parser/lexer"
+	"github.com/expr-lang/expr/parser/operator"
+	"github.com/expr-lang/expr/parser/utils"
+)
+
+type arg byte
+
+const (
+	expr arg = 1 << iota
+	predicate
+)
+
+const optional arg = 1 << 7
+
+var predicates = map[string]struct {
+	args []arg
+}{
+	"all":           {[]arg{expr, predicate}},
+	"none":          {[]arg{expr, predicate}},
+	"any":           {[]arg{expr, predicate}},
+	"one":           {[]arg{expr, predicate}},
+	"filter":        {[]arg{expr, predicate}},
+	"map":           {[]arg{expr, predicate}},
+	"count":         {[]arg{expr, predicate | optional}},
+	"sum":           {[]arg{expr, predicate | optional}},
+	"find":          {[]arg{expr, predicate}},
+	"findIndex":     {[]arg{expr, predicate}},
+	"findLast":      {[]arg{expr, predicate}},
+	"findLastIndex": {[]arg{expr, predicate}},
+	"groupBy":       {[]arg{expr, predicate}},
+	"sortBy":        {[]arg{expr, predicate, expr | optional}},
+	"reduce":        {[]arg{expr, predicate, expr | optional}},
+}
+
+type parser struct {
+	tokens    []Token
+	current   Token
+	pos       int
+	err       *file.Error
+	config    *conf.Config
+	depth     int  // predicate call depth
+	nodeCount uint // tracks number of AST nodes created
+}
+
+func (p *parser) checkNodeLimit() error {
+	p.nodeCount++
+	if p.config == nil {
+		if p.nodeCount > conf.DefaultMaxNodes {
+			p.error("compilation failed: expression exceeds maximum allowed nodes")
+			return nil
+		}
+		return nil
+	}
+	if p.config.MaxNodes > 0 && p.nodeCount > p.config.MaxNodes {
+		p.error("compilation failed: expression exceeds maximum allowed nodes")
+		return nil
+	}
+	return nil
+}
+
+func (p *parser) createNode(n Node, loc file.Location) Node {
+	if err := p.checkNodeLimit(); err != nil {
+		return nil
+	}
+	if n == nil || p.err != nil {
+		return nil
+	}
+	n.SetLocation(loc)
+	return n
+}
+
+func (p *parser) createMemberNode(n *MemberNode, loc file.Location) *MemberNode {
+	if err := p.checkNodeLimit(); err != nil {
+		return nil
+	}
+	if n == nil || p.err != nil {
+		return nil
+	}
+	n.SetLocation(loc)
+	return n
+}
+
+type Tree struct {
+	Node   Node
+	Source file.Source
+}
+
+func Parse(input string) (*Tree, error) {
+	return ParseWithConfig(input, nil)
+}
+
+func ParseWithConfig(input string, config *conf.Config) (*Tree, error) {
+	source := file.NewSource(input)
+
+	tokens, err := Lex(source)
+	if err != nil {
+		return nil, err
+	}
+
+	p := &parser{
+		tokens:  tokens,
+		current: tokens[0],
+		config:  config,
+	}
+
+	node := p.parseSequenceExpression()
+
+	if !p.current.Is(EOF) {
+		p.error("unexpected token %v", p.current)
+	}
+
+	tree := &Tree{
+		Node:   node,
+		Source: source,
+	}
+
+	if p.err != nil {
+		return tree, p.err.Bind(source)
+	}
+
+	return tree, nil
+}
+
+func (p *parser) error(format string, args ...any) {
+	p.errorAt(p.current, format, args...)
+}
+
+func (p *parser) errorAt(token Token, format string, args ...any) {
+	if p.err == nil { // show first error
+		p.err = &file.Error{
+			Location: token.Location,
+			Message:  fmt.Sprintf(format, args...),
+		}
+	}
+}
+
+func (p *parser) next() {
+	p.pos++
+	if p.pos >= len(p.tokens) {
+		p.error("unexpected end of expression")
+		return
+	}
+	p.current = p.tokens[p.pos]
+}
+
+func (p *parser) expect(kind Kind, values ...string) {
+	if p.current.Is(kind, values...) {
+		p.next()
+		return
+	}
+	p.error("unexpected token %v", p.current)
+}
+
+// parse functions
+
+func (p *parser) parseSequenceExpression() Node {
+	nodes := []Node{p.parseExpression(0)}
+
+	for p.current.Is(Operator, ";") && p.err == nil {
+		p.next()
+		// If a trailing semicolon is present, break out.
+		if p.current.Is(EOF) {
+			break
+		}
+		nodes = append(nodes, p.parseExpression(0))
+	}
+
+	if len(nodes) == 1 {
+		return nodes[0]
+	}
+
+	return p.createNode(&SequenceNode{
+		Nodes: nodes,
+	}, nodes[0].Location())
+}
+
+func (p *parser) parseExpression(precedence int) Node {
+	if p.err != nil {
+		return nil
+	}
+
+	if precedence == 0 && p.current.Is(Operator, "let") {
+		return p.parseVariableDeclaration()
+	}
+
+	if precedence == 0 && p.current.Is(Operator, "if") {
+		return p.parseConditionalIf()
+	}
+
+	nodeLeft := p.parsePrimary()
+
+	prevOperator := ""
+	opToken := p.current
+	for opToken.Is(Operator) && p.err == nil {
+		negate := opToken.Is(Operator, "not")
+		var notToken Token
+
+		// Handle "not *" operator, like "not in" or "not contains".
+		if negate {
+			currentPos := p.pos
+			p.next()
+			if operator.AllowedNegateSuffix(p.current.Value) {
+				if op, ok := operator.Binary[p.current.Value]; ok && op.Precedence >= precedence {
+					notToken = p.current
+					opToken = p.current
+				} else {
+					p.pos = currentPos
+					p.current = opToken
+					break
+				}
+			} else {
+				p.error("unexpected token %v", p.current)
+				break
+			}
+		}
+
+		if op, ok := operator.Binary[opToken.Value]; ok && op.Precedence >= precedence {
+			p.next()
+
+			if opToken.Value == "|" {
+				identToken := p.current
+				p.expect(Identifier)
+				nodeLeft = p.parseCall(identToken, []Node{nodeLeft}, true)
+				goto next
+			}
+
+			if prevOperator == "??" && opToken.Value != "??" && !opToken.Is(Bracket, "(") {
+				p.errorAt(opToken, "Operator (%v) and coalesce expressions (??) cannot be mixed. Wrap either by parentheses.", opToken.Value)
+				break
+			}
+
+			if operator.IsComparison(opToken.Value) {
+				nodeLeft = p.parseComparison(nodeLeft, opToken, op.Precedence)
+				goto next
+			}
+
+			var nodeRight Node
+			if op.Associativity == operator.Left {
+				nodeRight = p.parseExpression(op.Precedence + 1)
+			} else {
+				nodeRight = p.parseExpression(op.Precedence)
+			}
+
+			nodeLeft = p.createNode(&BinaryNode{
+				Operator: opToken.Value,
+				Left:     nodeLeft,
+				Right:    nodeRight,
+			}, opToken.Location)
+			if nodeLeft == nil {
+				return nil
+			}
+
+			if negate {
+				nodeLeft = p.createNode(&UnaryNode{
+					Operator: "not",
+					Node:     nodeLeft,
+				}, notToken.Location)
+				if nodeLeft == nil {
+					return nil
+				}
+			}
+
+			goto next
+		}
+		break
+
+	next:
+		prevOperator = opToken.Value
+		opToken = p.current
+	}
+
+	if precedence == 0 {
+		nodeLeft = p.parseConditional(nodeLeft)
+	}
+
+	return nodeLeft
+}
+
+func (p *parser) parseVariableDeclaration() Node {
+	p.expect(Operator, "let")
+	variableName := p.current
+	p.expect(Identifier)
+	p.expect(Operator, "=")
+	value := p.parseExpression(0)
+	p.expect(Operator, ";")
+	node := p.parseSequenceExpression()
+	return p.createNode(&VariableDeclaratorNode{
+		Name:  variableName.Value,
+		Value: value,
+		Expr:  node,
+	}, variableName.Location)
+}
+
+func (p *parser) parseConditionalIf() Node {
+	p.next()
+	nodeCondition := p.parseExpression(0)
+	p.expect(Bracket, "{")
+	expr1 := p.parseSequenceExpression()
+	p.expect(Bracket, "}")
+	p.expect(Operator, "else")
+	p.expect(Bracket, "{")
+	expr2 := p.parseSequenceExpression()
+	p.expect(Bracket, "}")
+
+	return &ConditionalNode{
+		Cond: nodeCondition,
+		Exp1: expr1,
+		Exp2: expr2,
+	}
+
+}
+
+func (p *parser) parseConditional(node Node) Node {
+	var expr1, expr2 Node
+	for p.current.Is(Operator, "?") && p.err == nil {
+		p.next()
+
+		if !p.current.Is(Operator, ":") {
+			expr1 = p.parseExpression(0)
+			p.expect(Operator, ":")
+			expr2 = p.parseExpression(0)
+		} else {
+			p.next()
+			expr1 = node
+			expr2 = p.parseExpression(0)
+		}
+
+		node = p.createNode(&ConditionalNode{
+			Cond: node,
+			Exp1: expr1,
+			Exp2: expr2,
+		}, p.current.Location)
+		if node == nil {
+			return nil
+		}
+	}
+	return node
+}
+
+func (p *parser) parsePrimary() Node {
+	token := p.current
+
+	if token.Is(Operator) {
+		if op, ok := operator.Unary[token.Value]; ok {
+			p.next()
+			expr := p.parseExpression(op.Precedence)
+			node := p.createNode(&UnaryNode{
+				Operator: token.Value,
+				Node:     expr,
+			}, token.Location)
+			if node == nil {
+				return nil
+			}
+			return p.parsePostfixExpression(node)
+		}
+	}
+
+	if token.Is(Bracket, "(") {
+		p.next()
+		expr := p.parseSequenceExpression()
+		p.expect(Bracket, ")") // "an opened parenthesis is not properly closed"
+		return p.parsePostfixExpression(expr)
+	}
+
+	if p.depth > 0 {
+		if token.Is(Operator, "#") || token.Is(Operator, ".") {
+			name := ""
+			if token.Is(Operator, "#") {
+				p.next()
+				if p.current.Is(Identifier) {
+					name = p.current.Value
+					p.next()
+				}
+			}
+			node := p.createNode(&PointerNode{Name: name}, token.Location)
+			if node == nil {
+				return nil
+			}
+			return p.parsePostfixExpression(node)
+		}
+	}
+
+	if token.Is(Operator, "::") {
+		p.next()
+		token = p.current
+		p.expect(Identifier)
+		return p.parsePostfixExpression(p.parseCall(token, []Node{}, false))
+	}
+
+	return p.parseSecondary()
+}
+
+func (p *parser) parseSecondary() Node {
+	var node Node
+	token := p.current
+
+	switch token.Kind {
+
+	case Identifier:
+		p.next()
+		switch token.Value {
+		case "true":
+			node = p.createNode(&BoolNode{Value: true}, token.Location)
+			if node == nil {
+				return nil
+			}
+			return node
+		case "false":
+			node = p.createNode(&BoolNode{Value: false}, token.Location)
+			if node == nil {
+				return nil
+			}
+			return node
+		case "nil":
+			node = p.createNode(&NilNode{}, token.Location)
+			if node == nil {
+				return nil
+			}
+			return node
+		default:
+			if p.current.Is(Bracket, "(") {
+				node = p.parseCall(token, []Node{}, true)
+			} else {
+				node = p.createNode(&IdentifierNode{Value: token.Value}, token.Location)
+				if node == nil {
+					return nil
+				}
+			}
+		}
+
+	case Number:
+		p.next()
+		value := strings.Replace(token.Value, "_", "", -1)
+		var node Node
+		valueLower := strings.ToLower(value)
+		switch {
+		case strings.HasPrefix(valueLower, "0x"):
+			number, err := strconv.ParseInt(value, 0, 64)
+			if err != nil {
+				p.error("invalid hex literal: %v", err)
+			}
+			node = p.toIntegerNode(number)
+		case strings.ContainsAny(valueLower, ".e"):
+			number, err := strconv.ParseFloat(value, 64)
+			if err != nil {
+				p.error("invalid float literal: %v", err)
+			}
+			node = p.toFloatNode(number)
+		case strings.HasPrefix(valueLower, "0b"):
+			number, err := strconv.ParseInt(value, 0, 64)
+			if err != nil {
+				p.error("invalid binary literal: %v", err)
+			}
+			node = p.toIntegerNode(number)
+		case strings.HasPrefix(valueLower, "0o"):
+			number, err := strconv.ParseInt(value, 0, 64)
+			if err != nil {
+				p.error("invalid octal literal: %v", err)
+			}
+			node = p.toIntegerNode(number)
+		default:
+			number, err := strconv.ParseInt(value, 10, 64)
+			if err != nil {
+				p.error("invalid integer literal: %v", err)
+			}
+			node = p.toIntegerNode(number)
+		}
+		if node != nil {
+			node.SetLocation(token.Location)
+		}
+		return node
+	case String:
+		p.next()
+		node = p.createNode(&StringNode{Value: token.Value}, token.Location)
+		if node == nil {
+			return nil
+		}
+
+	default:
+		if token.Is(Bracket, "[") {
+			node = p.parseArrayExpression(token)
+		} else if token.Is(Bracket, "{") {
+			node = p.parseMapExpression(token)
+		} else {
+			p.error("unexpected token %v", token)
+		}
+	}
+
+	return p.parsePostfixExpression(node)
+}
+
+func (p *parser) toIntegerNode(number int64) Node {
+	if number > math.MaxInt {
+		p.error("integer literal is too large")
+		return nil
+	}
+	return p.createNode(&IntegerNode{Value: int(number)}, p.current.Location)
+}
+
+func (p *parser) toFloatNode(number float64) Node {
+	if number > math.MaxFloat64 {
+		p.error("float literal is too large")
+		return nil
+	}
+	return p.createNode(&FloatNode{Value: number}, p.current.Location)
+}
+
+func (p *parser) parseCall(token Token, arguments []Node, checkOverrides bool) Node {
+	var node Node
+
+	isOverridden := false
+	if p.config != nil {
+		isOverridden = p.config.IsOverridden(token.Value)
+	}
+	isOverridden = isOverridden && checkOverrides
+
+	if b, ok := predicates[token.Value]; ok && !isOverridden {
+		p.expect(Bracket, "(")
+
+		// In case of the pipe operator, the first argument is the left-hand side
+		// of the operator, so we do not parse it as an argument inside brackets.
+		args := b.args[len(arguments):]
+
+		for i, arg := range args {
+			if arg&optional == optional {
+				if p.current.Is(Bracket, ")") {
+					break
+				}
+			} else {
+				if p.current.Is(Bracket, ")") {
+					p.error("expected at least %d arguments", len(args))
+				}
+			}
+
+			if i > 0 {
+				p.expect(Operator, ",")
+			}
+			var node Node
+			switch {
+			case arg&expr == expr:
+				node = p.parseExpression(0)
+			case arg&predicate == predicate:
+				node = p.parsePredicate()
+			}
+			arguments = append(arguments, node)
+		}
+
+		// skip last comma
+		if p.current.Is(Operator, ",") {
+			p.next()
+		}
+		p.expect(Bracket, ")")
+
+		node = p.createNode(&BuiltinNode{
+			Name:      token.Value,
+			Arguments: arguments,
+		}, token.Location)
+		if node == nil {
+			return nil
+		}
+	} else if _, ok := builtin.Index[token.Value]; ok && (p.config == nil || !p.config.Disabled[token.Value]) && !isOverridden {
+		node = p.createNode(&BuiltinNode{
+			Name:      token.Value,
+			Arguments: p.parseArguments(arguments),
+		}, token.Location)
+		if node == nil {
+			return nil
+		}
+
+	} else {
+		callee := p.createNode(&IdentifierNode{Value: token.Value}, token.Location)
+		if callee == nil {
+			return nil
+		}
+		node = p.createNode(&CallNode{
+			Callee:    callee,
+			Arguments: p.parseArguments(arguments),
+		}, token.Location)
+		if node == nil {
+			return nil
+		}
+	}
+	return node
+}
+
+func (p *parser) parseArguments(arguments []Node) []Node {
+	// If pipe operator is used, the first argument is the left-hand side
+	// of the operator, so we do not parse it as an argument inside brackets.
+	offset := len(arguments)
+
+	p.expect(Bracket, "(")
+	for !p.current.Is(Bracket, ")") && p.err == nil {
+		if len(arguments) > offset {
+			p.expect(Operator, ",")
+		}
+		if p.current.Is(Bracket, ")") {
+			break
+		}
+		node := p.parseExpression(0)
+		arguments = append(arguments, node)
+	}
+	p.expect(Bracket, ")")
+
+	return arguments
+}
+
+func (p *parser) parsePredicate() Node {
+	startToken := p.current
+	withBrackets := false
+	if p.current.Is(Bracket, "{") {
+		p.next()
+		withBrackets = true
+	}
+
+	p.depth++
+	var node Node
+	if withBrackets {
+		node = p.parseSequenceExpression()
+	} else {
+		node = p.parseExpression(0)
+		if p.current.Is(Operator, ";") {
+			p.error("wrap predicate with brackets { and }")
+		}
+	}
+	p.depth--
+
+	if withBrackets {
+		p.expect(Bracket, "}")
+	}
+	predicateNode := p.createNode(&PredicateNode{
+		Node: node,
+	}, startToken.Location)
+	if predicateNode == nil {
+		return nil
+	}
+	return predicateNode
+}
+
+func (p *parser) parseArrayExpression(token Token) Node {
+	nodes := make([]Node, 0)
+
+	p.expect(Bracket, "[")
+	for !p.current.Is(Bracket, "]") && p.err == nil {
+		if len(nodes) > 0 {
+			p.expect(Operator, ",")
+			if p.current.Is(Bracket, "]") {
+				goto end
+			}
+		}
+		node := p.parseExpression(0)
+		nodes = append(nodes, node)
+	}
+end:
+	p.expect(Bracket, "]")
+
+	node := p.createNode(&ArrayNode{Nodes: nodes}, token.Location)
+	if node == nil {
+		return nil
+	}
+	return node
+}
+
+func (p *parser) parseMapExpression(token Token) Node {
+	p.expect(Bracket, "{")
+
+	nodes := make([]Node, 0)
+	for !p.current.Is(Bracket, "}") && p.err == nil {
+		if len(nodes) > 0 {
+			p.expect(Operator, ",")
+			if p.current.Is(Bracket, "}") {
+				goto end
+			}
+			if p.current.Is(Operator, ",") {
+				p.error("unexpected token %v", p.current)
+			}
+		}
+
+		var key Node
+		// Map key can be one of:
+		//  * number
+		//  * string
+		//  * identifier, which is equivalent to a string
+		//  * expression, which must be enclosed in parentheses -- (1 + 2)
+		if p.current.Is(Number) || p.current.Is(String) || p.current.Is(Identifier) {
+			key = p.createNode(&StringNode{Value: p.current.Value}, p.current.Location)
+			if key == nil {
+				return nil
+			}
+			p.next()
+		} else if p.current.Is(Bracket, "(") {
+			key = p.parseExpression(0)
+		} else {
+			p.error("a map key must be a quoted string, a number, a identifier, or an expression enclosed in parentheses (unexpected token %v)", p.current)
+		}
+
+		p.expect(Operator, ":")
+
+		node := p.parseExpression(0)
+		pair := p.createNode(&PairNode{Key: key, Value: node}, token.Location)
+		if pair == nil {
+			return nil
+		}
+		nodes = append(nodes, pair)
+	}
+
+end:
+	p.expect(Bracket, "}")
+
+	node := p.createNode(&MapNode{Pairs: nodes}, token.Location)
+	if node == nil {
+		return nil
+	}
+	return node
+}
+
+func (p *parser) parsePostfixExpression(node Node) Node {
+	postfixToken := p.current
+	for (postfixToken.Is(Operator) || postfixToken.Is(Bracket)) && p.err == nil {
+		optional := postfixToken.Value == "?."
+	parseToken:
+		if postfixToken.Value == "." || postfixToken.Value == "?." {
+			p.next()
+
+			propertyToken := p.current
+			if optional && propertyToken.Is(Bracket, "[") {
+				postfixToken = propertyToken
+				goto parseToken
+			}
+			p.next()
+
+			if propertyToken.Kind != Identifier &&
+				// Operators like "not" and "matches" are valid methods or property names.
+				(propertyToken.Kind != Operator || !utils.IsValidIdentifier(propertyToken.Value)) {
+				p.error("expected name")
+			}
+
+			property := p.createNode(&StringNode{Value: propertyToken.Value}, propertyToken.Location)
+			if property == nil {
+				return nil
+			}
+
+			chainNode, isChain := node.(*ChainNode)
+			optional := postfixToken.Value == "?."
+
+			if isChain {
+				node = chainNode.Node
+			}
+
+			memberNode := p.createMemberNode(&MemberNode{
+				Node:     node,
+				Property: property,
+				Optional: optional,
+			}, propertyToken.Location)
+			if memberNode == nil {
+				return nil
+			}
+
+			if p.current.Is(Bracket, "(") {
+				memberNode.Method = true
+				node = p.createNode(&CallNode{
+					Callee:    memberNode,
+					Arguments: p.parseArguments([]Node{}),
+				}, propertyToken.Location)
+				if node == nil {
+					return nil
+				}
+			} else {
+				node = memberNode
+			}
+
+			if isChain || optional {
+				node = p.createNode(&ChainNode{Node: node}, propertyToken.Location)
+				if node == nil {
+					return nil
+				}
+			}
+
+		} else if postfixToken.Value == "[" {
+			p.next()
+			var from, to Node
+
+			if p.current.Is(Operator, ":") { // slice without from [:1]
+				p.next()
+
+				if !p.current.Is(Bracket, "]") { // slice without from and to [:]
+					to = p.parseExpression(0)
+				}
+
+				node = p.createNode(&SliceNode{
+					Node: node,
+					To:   to,
+				}, postfixToken.Location)
+				if node == nil {
+					return nil
+				}
+				p.expect(Bracket, "]")
+
+			} else {
+
+				from = p.parseExpression(0)
+
+				if p.current.Is(Operator, ":") {
+					p.next()
+
+					if !p.current.Is(Bracket, "]") { // slice without to [1:]
+						to = p.parseExpression(0)
+					}
+
+					node = p.createNode(&SliceNode{
+						Node: node,
+						From: from,
+						To:   to,
+					}, postfixToken.Location)
+					if node == nil {
+						return nil
+					}
+					p.expect(Bracket, "]")
+
+				} else {
+					// Slice operator [:] was not found,
+					// it should be just an index node.
+					node = p.createNode(&MemberNode{
+						Node:     node,
+						Property: from,
+						Optional: optional,
+					}, postfixToken.Location)
+					if node == nil {
+						return nil
+					}
+					if optional {
+						node = p.createNode(&ChainNode{Node: node}, postfixToken.Location)
+						if node == nil {
+							return nil
+						}
+					}
+					p.expect(Bracket, "]")
+				}
+			}
+		} else {
+			break
+		}
+		postfixToken = p.current
+	}
+	return node
+}
+func (p *parser) parseComparison(left Node, token Token, precedence int) Node {
+	var rootNode Node
+	for {
+		comparator := p.parseExpression(precedence + 1)
+		cmpNode := p.createNode(&BinaryNode{
+			Operator: token.Value,
+			Left:     left,
+			Right:    comparator,
+		}, token.Location)
+		if cmpNode == nil {
+			return nil
+		}
+		if rootNode == nil {
+			rootNode = cmpNode
+		} else {
+			rootNode = p.createNode(&BinaryNode{
+				Operator: "&&",
+				Left:     rootNode,
+				Right:    cmpNode,
+			}, token.Location)
+			if rootNode == nil {
+				return nil
+			}
+		}
+
+		left = comparator
+		token = p.current
+		if !(token.Is(Operator) && operator.IsComparison(token.Value) && p.err == nil) {
+			break
+		}
+		p.next()
+	}
+	return rootNode
+}