Touring XQuery/XPath

These notes are to inform the SPARQL Invocation instructions. This document is not endorsed by W3C, the XQuery working group, or anyone at all.

<root>
  <example name="roadmap">
{
doc('http://www.w3.org/2005/11/XQuery-evaluation-recipies.html')//div[id='roadmap']/pre/@text()
}
  </example>
</root>

involves the following documents:

• ^XQ Constructors — The XML elements around the {}'s follow the constructor grammar.

  [1]	Module	::=	VersionDecl? (LibraryModule | MainModule)
  [3]	MainModule	::=	Prolog QueryBody
  [30]	QueryBody	::=	Expr
  [31]	Expr	::=	ExprSingle ("," ExprSingle)*
  [32]	ExprSingle	::=	FLWORExpr | QuantifiedExpr | TypeswitchExpr | IfExpr | OrExpr
  [46]	OrExpr	::=	AndExpr ( "or" AndExpr )*
  [47]	AndExpr	::=	ComparisonExpr ( "and" ComparisonExpr )*
  [48]	ComparisonExpr	::=	RangeExpr ( (ValueComp | GeneralComp | NodeComp) RangeExpr )?
  [49]	RangeExpr	::=	AdditiveExpr ( "to" AdditiveExpr )?
  [50]	AdditiveExpr	::=	MultiplicativeExpr ( ("+" | "-") MultiplicativeExpr )*
  [51]	MultiplicativeExpr	::=	UnionExpr ( ("*" | "div" | "idiv" | "mod") UnionExpr )*
  [52]	UnionExpr	::=	IntersectExceptExpr ( ("union" | "|") IntersectExceptExpr )*
  [53]	IntersectExceptExpr	::=	InstanceofExpr ( ("intersect" | "except") InstanceofExpr )*
  [54]	InstanceofExpr	::=	TreatExpr ( "instance" "of" SequenceType )?
  [55]	TreatExpr	::=	CastableExpr ( "treat" "as" SequenceType )?
  [56]	CastableExpr	::=	CastExpr ( "castable" "as" SingleType )?
  [57]	CastExpr	::=	UnaryExpr ( "cast" "as" SingleType )?
  [58]	UnaryExpr	::=	("-" | "+")* ValueExpr
  [59]	ValueExpr	::=	ValidateExpr | PathExpr | ExtensionExpr
  [68]	PathExpr	::=	("/" RelativePathExpr?) | ("//" RelativePathExpr) | RelativePathExpr	/* xgs: leading-lone-slash */
  [69]	RelativePathExpr	::=	StepExpr (("/" | "//") StepExpr)*
  [70]	StepExpr	::=	FilterExpr | AxisStep
  [80]	Wildcard	::=	"*" | (NCName ":" "*") | ("*" ":" NCName)	/* ws: explicit */
  [81]	FilterExpr	::=	PrimaryExpr PredicateList
  [84]	PrimaryExpr	::=	Literal | VarRef | ParenthesizedExpr | ContextItemExpr | FunctionCall | OrderedExpr | UnorderedExpr | Constructor
  [94]	Constructor	::=	DirectConstructor | ComputedConstructor
  [95]	DirectConstructor	::=	DirElemConstructor | DirCommentConstructor | DirPIConstructor
  [96]	DirElemConstructor	::=	"<" QName DirAttributeList ("/>" | (">" DirElemContent* "</" QName S? ">"))
  [101]	DirElemContent	::=	DirectConstructor | CDataSection | CommonContent | ElementContentChar
  [148]	ElementContentChar	::=	Char - [{}<&]
  [102]	CommonContent	::=	PredefinedEntityRef | CharRef | "{{" | "}}" | EnclosedExpr
  [107]	CDataSection	::=	"<![CDATA[" CDataSectionContents "]]>"
  [108]	CDataSectionContents	::=	(Char* - (Char* ']]>' Char*))
  [97]	DirAttributeList	::=	(S (QName S? "=" S? DirAttributeValue)?)*
  [98]	DirAttributeValue	::=	('"' (EscapeQuot | QuotAttrValueContent)* '"') | ("'" (EscapeApos | AposAttrValueContent)* "'")
  [99]	QuotAttrValueContent	::=	QuotAttrContentChar | CommonContent
  [100]	AposAttrValueContent	::=	AposAttrContentChar | CommonContent
  [149]	QuotAttrContentChar	::=	Char - ["{}<&]
  [150]	AposAttrContentChar	::=	Char - ['{}<&]
  [146]	EscapeQuot	::=	'""'
  [147]	EscapeApos	::=	"''"
  [29]	EnclosedExpr	::=	"{" Expr "}"

• ^XQ Expresson Processing — describes the static and dynamic type evaluation phases.
• ^XQ Function Calls — describes argument conversion and function evaluation; supports the FunctionCall production.

  [93]

  FunctionCall

  ::=

  QName "(" (ExprSingle ("," ExprSingle)*)? ")"

• ^XQ Path Expressions — evaluation of steps relative to a context node.

  [68]	PathExpr	::=	("/" RelativePathExpr?) | ("//" RelativePathExpr) | RelativePathExpr
  [69]	RelativePathExpr	::=	StepExpr (("/" | "//") StepExpr)*

• ^XQ Predicates — filter a sequence by comparing singleton results to the current context and calculating the Effective Boolean Value of others; supports the Predicate production

  [83]

  Predicate

  ::=

  "[" Expr "]"

• ^XQ Effective Boolean Value — calls fn:boolean to create an xsd:boolean from an input sequence.
  also documented in ^XP Effective Boolean Value.
• ^XP fn:boolean —
• ^XQ Logical Expressions —
• ^XQ Comparison Expressions —
• ^XQ Arithmetic Expressions —
• ^XQ Function Calls —
• ^XQ Types are based on XML Schema —
• ^XP Effective Boolean Value —
• ^XP expression processing —

SPARQL's FILTER Evalution

SPARQL offers query constraints similar to SQL's WHERE function. The specification of SPARQL constraints is designed to be compatible with XQuery predicate evaluation. Casting Constructor Functions check Extensions Extensions.

SPARQL does not currently emulate the following possibly applicable behavior from XQuery:

1. URI promotion — xsd:anyURI => xsd:string when the latter is needed.
2. conversion of xsd:untypedAtomic — xsd:untypedAtomic => expected type, xsd:double for numeric arguments