Mihaela Mihaljevic
d83e5a88ce
Compile and evaluate full XPath 1.0 expressions, not just location paths. Add the four-type Value (node-set, boolean, number, string) with the spec's coercion rules and canonical number formatting, a recursive-descent parser for the operator grammar (or/and, equality, relational, additive, multiplicative, unary minus, union) whose grammatical position disambiguates * and the operator keywords, function calls, variable references, and filter expressions. Predicates are now arbitrary expressions (a numeric predicate is a position test). Comparison follows the node-set quantification rules. Query gains value/number/string/boolean accessors and a $variable binding map; the core functions last, position, count, not, true, false, boolean, number, and string ship with it. Closes #42
127 lines
4.2 KiB
Swift
127 lines
4.2 KiB
Swift
@testable import PureXML
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import Testing
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@Suite("XPath expressions")
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struct XPathExpressionTests {
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private func shop() throws -> PureXML.Model.Node {
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try PureXML.parse(
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"<shop>"
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+ "<book id=\"b1\"><title>A</title><price>10</price></book>"
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+ "<book id=\"b2\"><title>B</title><price>30</price></book>"
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+ "<book id=\"b3\"><title>C</title><price>50</price></book>"
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+ "</shop>",
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)
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}
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private func number(_ path: String) throws -> Double {
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try PureXML.XPath.Query(path).number(over: shop())
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}
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private func string(_ path: String) throws -> String {
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try PureXML.XPath.Query(path).string(over: shop())
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}
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private func boolean(_ path: String) throws -> Bool {
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try PureXML.XPath.Query(path).boolean(over: shop())
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}
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// MARK: Arithmetic and precedence
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@Test("Arithmetic honors precedence")
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func test_arithmetic() throws {
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#expect(try number("2 + 3 * 4") == 14)
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#expect(try number("(2 + 3) * 4") == 20)
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#expect(try number("7 mod 3") == 1)
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#expect(try number("10 div 4") == 2.5)
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#expect(try number("-5 + 2") == -3)
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}
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// MARK: The four types and coercion
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@Test("Numbers render in the XPath canonical form")
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func test_numberFormatting() throws {
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#expect(try string("3") == "3")
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#expect(try string("1 div 2") == "0.5")
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#expect(try string("1 div 0") == "Infinity")
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#expect(try string("0 div 0") == "NaN")
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}
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@Test("Booleans coerce to strings and numbers")
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func test_booleanCoercion() throws {
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#expect(try string("1 = 1") == "true")
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#expect(try string("1 = 2") == "false")
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#expect(try number("true()") == 1)
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}
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@Test("count and node-set string-value")
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func test_nodeSetFunctions() throws {
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#expect(try number("count(//book)") == 3)
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#expect(try string("//title") == "A")
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}
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// MARK: Comparison
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@Test("Relational comparison over node-sets is existential")
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func test_relational() throws {
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#expect(try boolean("//price > 40"))
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#expect(try boolean("//price < 20"))
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#expect(try !boolean("//price > 100"))
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}
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@Test("Equality against a node-set matches any member")
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func test_nodeSetEquality() throws {
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#expect(try boolean("//book/@id = 'b2'"))
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#expect(try !boolean("//book/@id = 'zz'"))
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}
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@Test("Boolean operators and not()")
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func test_booleanLogic() throws {
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#expect(try boolean("1 = 1 and 2 = 2"))
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#expect(try !boolean("1 = 1 and 2 = 3"))
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#expect(try boolean("1 = 2 or 3 = 3"))
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#expect(try boolean("not(1 = 2)"))
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}
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// MARK: Predicates as expressions
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@Test("Numeric and function predicates select positionally")
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func test_predicates() throws {
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#expect(try PureXML.XPath.Query("//book[position()=2]/@id").strings(over: shop()) == ["b2"])
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#expect(try PureXML.XPath.Query("//book[last()]/@id").strings(over: shop()) == ["b3"])
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#expect(try PureXML.XPath.Query("//book[price>20]/@id").strings(over: shop()) == ["b2", "b3"])
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}
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// MARK: Union
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@Test("Union merges node-sets in document order without duplicates")
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func test_union() throws {
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let titles = try PureXML.XPath.Query("//title | //price").evaluate(over: shop())
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#expect(titles.count == 6)
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}
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// MARK: Variables
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@Test("Variable references resolve from the binding map")
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func test_variables() throws {
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let query = try PureXML.XPath.Query("$base + count(//book)")
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let value = try query.number(over: shop(), variables: ["base": .number(10)])
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#expect(value == 13)
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}
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@Test("An unbound variable is an error")
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func test_unboundVariable() throws {
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let query = try PureXML.XPath.Query("$missing")
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#expect(throws: PureXML.XPath.QueryError.self) {
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_ = try query.value(over: shop())
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}
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}
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@Test("An unknown function is an error")
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func test_unknownFunction() throws {
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let query = try PureXML.XPath.Query("bogus()")
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#expect(throws: PureXML.XPath.QueryError.self) {
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_ = try query.value(over: shop())
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}
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}
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}
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