filter_parser.go

package godata

const (
	FilterTokenOpenParen int = iota
	FilterTokenCloseParen
	FilterTokenWhitespace
	FilterTokenNav
	FilterTokenColon // for 'any' and 'all' lambda operators
	FilterTokenComma
	FilterTokenLogical
	FilterTokenOp
	FilterTokenFunc
	FilterTokenLambda
	FilterTokenNull
	FilterTokenIt
	FilterTokenRoot
	FilterTokenFloat
	FilterTokenInteger
	FilterTokenString
	FilterTokenDate
	FilterTokenTime
	FilterTokenDateTime
	FilterTokenBoolean
	FilterTokenLiteral
)

var GlobalFilterTokenizer = FilterTokenizer()
var GlobalFilterParser = FilterParser()

// Convert an input string from the $filter part of the URL into a parse
// tree that can be used by providers to create a response.
func ParseFilterString(filter string) (*GoDataFilterQuery, error) {
	tokens, err := GlobalFilterTokenizer.Tokenize(filter)
	if err != nil {
		return nil, err
	}
	// TODO: can we do this in one fell swoop?
	postfix, err := GlobalFilterParser.InfixToPostfix(tokens)
	if err != nil {
		return nil, err
	}
	tree, err := GlobalFilterParser.PostfixToTree(postfix)
	if err != nil {
		return nil, err
	}
	return &GoDataFilterQuery{tree}, nil
}

// Create a tokenizer capable of tokenizing filter statements
func FilterTokenizer() *Tokenizer {
	t := Tokenizer{}
	t.Add("^[0-9]{4,4}-[0-9]{2,2}-[0-9]{2,2}T[0-9]{2,2}:[0-9]{2,2}(:[0-9]{2,2}(.[0-9]+)?)?(Z|[+-][0-9]{2,2}:[0-9]{2,2})", FilterTokenDateTime)
	t.Add("^-?[0-9]{4,4}-[0-9]{2,2}-[0-9]{2,2}", FilterTokenDate)
	t.Add("^[0-9]{2,2}:[0-9]{2,2}(:[0-9]{2,2}(.[0-9]+)?)?", FilterTokenTime)
	t.Add("^\\(", FilterTokenOpenParen)
	t.Add("^\\)", FilterTokenCloseParen)
	t.Add("^/", FilterTokenNav)
	t.Add("^:", FilterTokenColon)
	t.Add("^,", FilterTokenComma)
	t.Add("^(eq|ne|gt|ge|lt|le|and|or|not|has)", FilterTokenLogical)
	t.Add("^(add|sub|mul|div|mod)", FilterTokenOp)
	t.Add("^(contains|endswith|startswith|length|indexof|substring|tolower|toupper|"+
		"trim|concat|year|month|day|hour|minute|second|fractionalseconds|date|"+
		"time|totaloffsetminutes|now|maxdatetime|mindatetime|totalseconds|round|"+
		"floor|ceiling|isof|cast|geo.distance|geo.intersects|geo.length)", FilterTokenFunc)
	t.Add("^(any|all)", FilterTokenLambda)
	t.Add("^null", FilterTokenNull)
	t.Add("^\\$it", FilterTokenIt)
	t.Add("^\\$root", FilterTokenRoot)
	t.Add("^-?[0-9]+\\.[0-9]+", FilterTokenFloat)
	t.Add("^-?[0-9]+", FilterTokenInteger)
	t.Add("^'(''|[^'])*'", FilterTokenString)
	t.Add("^[a-zA-Z][a-zA-Z0-9_.]*", FilterTokenLiteral)
	t.Ignore("^ ", FilterTokenWhitespace)

	return &t
}

func FilterParser() *Parser {
	parser := EmptyParser()
	parser.DefineOperator("/", 2, OpAssociationLeft, 8)
	parser.DefineOperator("has", 2, OpAssociationLeft, 8)
	parser.DefineOperator("-", 1, OpAssociationNone, 7)
	parser.DefineOperator("not", 1, OpAssociationLeft, 7)
	parser.DefineOperator("cast", 2, OpAssociationNone, 7)
	parser.DefineOperator("mul", 2, OpAssociationNone, 6)
	parser.DefineOperator("div", 2, OpAssociationNone, 6)
	parser.DefineOperator("mod", 2, OpAssociationNone, 6)
	parser.DefineOperator("add", 2, OpAssociationNone, 5)
	parser.DefineOperator("sub", 2, OpAssociationNone, 5)
	parser.DefineOperator("gt", 2, OpAssociationLeft, 4)
	parser.DefineOperator("ge", 2, OpAssociationLeft, 4)
	parser.DefineOperator("lt", 2, OpAssociationLeft, 4)
	parser.DefineOperator("le", 2, OpAssociationLeft, 4)
	parser.DefineOperator("isof", 2, OpAssociationLeft, 4)
	parser.DefineOperator("eq", 2, OpAssociationLeft, 3)
	parser.DefineOperator("ne", 2, OpAssociationLeft, 3)
	parser.DefineOperator("and", 2, OpAssociationLeft, 2)
	parser.DefineOperator("or", 2, OpAssociationLeft, 1)
	parser.DefineOperator(":", 2, OpAssociationLeft, 1)
	parser.DefineFunction("contains", 2)
	parser.DefineFunction("endswith", 2)
	parser.DefineFunction("startswith", 2)
	parser.DefineFunction("length", 1)
	parser.DefineFunction("indexof", 2)
	parser.DefineFunction("substring", 2)
	parser.DefineFunction("tolower", 1)
	parser.DefineFunction("toupper", 1)
	parser.DefineFunction("trim", 1)
	parser.DefineFunction("concat", 2)
	parser.DefineFunction("year", 1)
	parser.DefineFunction("month", 1)
	parser.DefineFunction("day", 1)
	parser.DefineFunction("hour", 1)
	parser.DefineFunction("minute", 1)
	parser.DefineFunction("second", 1)
	parser.DefineFunction("fractionalseconds", 1)
	parser.DefineFunction("date", 1)
	parser.DefineFunction("time", 1)
	parser.DefineFunction("totaloffsetminutes", 1)
	parser.DefineFunction("now", 0)
	parser.DefineFunction("maxdatetime", 0)
	parser.DefineFunction("mindatetime", 0)
	parser.DefineFunction("totalseconds", 1)
	parser.DefineFunction("round", 1)
	parser.DefineFunction("floor", 1)
	parser.DefineFunction("ceiling", 1)
	parser.DefineFunction("isof", 2)
	parser.DefineFunction("cast", 2)
	parser.DefineFunction("geo.distance", 2)
	parser.DefineFunction("geo.intesects", 2)
	parser.DefineFunction("geo.length", 1)
	parser.DefineFunction("any", 1)
	parser.DefineFunction("all", 1)

	return parser
}

func SemanticizeFilterQuery(
	filter *GoDataFilterQuery,
	service *GoDataService,
	entity *GoDataEntityType,
) error {

	if filter == nil || filter.Tree == nil {
		return nil
	}

	var semanticizeFilterNode func(node *ParseNode) error
	semanticizeFilterNode = func(node *ParseNode) error {

		if node.Token.Type == FilterTokenLiteral {
			prop, ok := service.PropertyLookup[entity][node.Token.Value]
			if !ok {
				return BadRequestError("No property found " + node.Token.Value + " on entity " + entity.Name)
			}
			node.Token.SemanticType = SemanticTypeProperty
			node.Token.SemanticReference = prop
		} else {
			node.Token.SemanticType = SemanticTypePropertyValue
			node.Token.SemanticReference = &node.Token.Value
		}

		for _, child := range node.Children {
			err := semanticizeFilterNode(child)
			if err != nil {
				return err
			}
		}

		return nil
	}

	return semanticizeFilterNode(filter.Tree)
}