\section{Introduction}
This paper presents {\MathQL} version 4 which is the latest version of the
-language, fully developed by Ferruccio Guidi.
+language, fully developed by the Author.
For a description of the previous versions of {\MathQL} see: \cite{Gui03}
(version 3), \cite{GS03} (version 2), \cite{Lor02} (version 1).
The main novelties of this version are the elimination of some cast operators
-(producing a substantial simplification in the query structure and semantics,
-see \secref{Operational}), a clear distinction between the core language and
-the auxiliary functions of the basic library, a support for query generating
-functions, the possibility of extending the language adding new libraries of
-functions and a more uniform textual syntax.
+(producing a substantial simplification in the query structure and semantics),
+a clear distinction between the core language and the auxiliary functions of
+the basic library, a support for query generating functions, the possibility
+of extending the language adding new libraries of functions and a more uniform
+textual syntax.
{\MathQL}.4 incorporates the features of {\MathQL}.3 not documented on paper%
\footnote
{See the ``what's new'' section of {\MathQL} Web Site:
-\URI{helm.cs.unibo.it/mathql}.}
+\CURI{helm.cs.unibo.it/mathql}.}
and adds some new features improving {\MathQL} capabilities to post-process
the query results.
-\subsection{Textual syntax}
-
-The syntax of grammatical productions resembles BNF and POSIX notation:
-
-\begin{itemize}
-
-\item
-\TT{::=} defines a grammatical production by means of a regular expression.
-
-Regular expressions are made of the following elements
-(here \TT{...} is a placeholder):
-
-% \item
-% \TT{.} represents any character between U 0020 and U 007F inclusive;
-
-\item
-\TT{`...`} represents any character in a character set;
-
-\item
-\verb+`^ ...`+ represents any character (U+0020 to U+007E) not in a character
-set;
-
-\item
-\TT{"..."} represents a string to be matched verbatim;
-
-\item
-\GP{...} represents a regular expression defined by a grammatical production;
-
-\item
-\TT{... ...} represents a conjunctive regular expression;
-
-\item
-\TT{... | ...} represents a disjunctive regular expression;
-
-\item
-\TT{[ ... ]?} represents an optional regular expression;
-
-\item
-\TT{[ ... ]+} represents a regular expression to be repeated one or more times;
-
-\item
-\TT{[ ... ]*} represents a regular expression to be repeated zero or more times;
-
-\item
-\TT{[ ... ]} represents a grouped regular expression.
-
-\end{itemize}
-
-\noindent
-{\MathQL} Expressions can contain quoted constant strings with the syntax of
-\figref {StrTS}.%
-\footnote{Note that the first slash of the \GP{path} is not optional as
-in {\MathQL}.3.}
-
-\begin{figure}[ht]
-\begin{footnotesize} \begin{verbatim}
-<dec> ::= '0 - 9'
-<num> ::= <dec> [ <dec> ]*
-<hex> ::= <dec> | 'A - F' | 'a - f'
-<escaped> ::= "u" <hex> <hex> <hex> <hex> | '"' | "\" | "^"
-<string> ::= '"' [ "\" <escaped> "^" | '^ "\^' ]* '"'
-<path> ::= "/" | [ "/" <string> ]+
-\end{verbatim} \end{footnotesize}
-\vskip-1pc
-\caption{Textual syntax of numbers, strings and paths} \label{StrTS}
-\end{figure}
-
-\noindent
-The meaning of the escaped sequences is shown in \figref{EscTS}
-(where $ .... $ is a 4-digit placeholder).
-
-\begin{figure}[ht]
-\begin{footnotesize}
-\begin{center} \begin{tabular}{|l|l|c|}
-\hline {\bf Escape sequence} & {\bf Unicode character} & {\bf Text} \\
-\hline \verb+\u....^+ & U+.... & \\
-\hline \verb+\"^+ & U+0022 & \verb+"+ \\
-\hline \verb+\\^+ & U+005C & \verb+\+ \\
-\hline \verb+\^^+ & U+005E & \verb+^+ \\
-\hline
-\end{tabular} \end{center}
-\end{footnotesize}
-\vskip-1pc
-\caption{Textual syntax of escaped characters} \label{EscTS}
-\end{figure}
-
-{\MathQL} character escaping syntax aims at complying with W3C character model
-for the World Wide Web \cite{W3Ca} which recommends a support for standard
-Unicode characters (U+0000 to U+FFFF) and escape sequences with
-start/end delimiters.
-In particular {\MathQL} escape delimiters (backslash and caret) are chosen
-among the {\em unwise} characters for URI references (see \cite{URI}) because
-URI references are the natural content of constant strings and these
-characters should not be so frequent in them.
-
-Query expressions can contain variables for {\av}'s (production \GP{avar})
-and variables for {\av} sets, {\ie} for query results (production \GP{svar})
-according to the syntax of \figref{VarTS}.
-
-\begin{figure}[ht]
-\begin{footnotesize} \begin{verbatim}
-<alpha> ::= [ 'A - Z' | 'a - z' | `_` ]+
-<id> ::= <alpha> [ <alpha> | <dec> ]*
-<avar> ::= "@" <id>
-<svar> ::= "$" <id>
-\end{verbatim}\end{footnotesize} %$
-\vskip-1pc
-\caption{Textual syntax of variables} \label{VarTS}
-\end{figure}
-
-\noindent
-The syntax of query expressions (production \GP{query}) is described in
-\figref{QueryTS}.
-
-\begin{figure}[ht]
-\begin{footnotesize} \begin{verbatim}
-<qualifier> ::= [ "inverse" ]? [ "sub" | "super" ]? <path>
-<main> ::= [ "main" <path> ]?
-<cons> ::= <path> [ "in" | "match" ] <query>
-<istrue> ::= [ "istrue" <cons> [ "," <cons> ]* ]?
-<isfalses> ::= [ "isfalse" <cons> [ "," <cons> ]* ]*
-<exp> ::= <path> [ "as" <path> ]?
-<sec> ::= [ "attr" <exp> [ "," <exp> ]* ]?
-<opt_args> ::= <main> <istrue> <isfalses> <sec>
-<source> ::= [ "pattern" ]? <query>
-<paths> ::= [ <path> [ "," <path> ]* ]?
-<query> ::= "(" <query> ")" | <string> | "[" <xavs> "]"
- | "property" <qualifier> <opt_args> "of" <source>
- | "let" <svar> "=" <query> "in" <query>
- | <query> ";;" <query> | <svar> | <avar>
- | "ex" <query> | <avar> "." <path>
- | "add" [ "distr" ]? [ <xgroups> | <avar> ] "in" <query>
- | "for" <avar> "in" <query> [ "sup" | "inf" ] <query>
- | "while" <query> [ "sup" | "inf" ] <query>
- | <path> "{" <paths> "}" "{" <queries> "}"
- | "gen" <path> [ "{" <queries> "}" | "in" <query> ]
-<queries> ::= [ <query> [ "," <query> ]* ]?
-<xattr> ::= <path> "=" <query>
-<xgroup> ::= "{" <xattr> [ ";" <xattr> ]* "}"
-<xgroups> ::= <xgroup> [ "," <xgroup> ]*
-<xav> ::= <string> [ "attr" <xgroups> ]?
-<xavs> ::= [ <xav> [ ";" <xav> ]* ]?
-\end{verbatim} \end{footnotesize}
-\vskip-1pc
-\caption{Textual syntax of queries} \label{QueryTS}
-\end{figure}
-
-\noindent
-The syntax of result expressions (production \GP{avs}) is described in
-\figref{ResultTS}.
-
-\begin{figure}[ht]
-\begin{footnotesize} \begin{verbatim}
-<attr> ::= <path> "=" "{" [ <string> [ "," <string> ]* ]? "}"
-<group> ::= "{" <attr> [ ";" <attr> ]* "}"
-<av> ::= <string> [ "attr" <group> [ "," <group> ]* ]?
-<avs> ::= [ <av> [ ";" <av> ]* ]?
-\end{verbatim} \end{footnotesize}
-\vskip-1pc
-\caption{Textual syntax of results} \label{ResultTS}
-\end{figure}
-
-\xcomment {
-
-\begin{figure}[ht]
-\begin{footnotesize} \begin{verbatim}
- | "select" <avar> "from" <query> "where" <query>
-\end{verbatim} \end{footnotesize}
-\vskip-1pc
-\caption{Textual syntax of basic query extensions} \label{BasicTS}
-\end{figure}
-
-}
+\input{mathql_introduction_avsets}
+\input{mathql_introduction_property}
+\input{mathql_introduction_core}
+\input{mathql_introduction_basic}
+\input{mathql_introduction_textual}
projects / helm.git / blobdiff