-@or "dylan" "zimmerman"
-
-@set Result-1
-
-@or @and bob dylan @set Result-1
-
-@attr 4=1 @and @attr 1=1 "bob dylan" @attr 1=4 "slow train coming"
-
-@attr 4=1 @attr 1=4 "self portrait"
-
-@prox 0 3 1 2 k 2 dylan zimmerman
-</screen>
-
-</sect2>
-<sect2><title id="CCL">Common Command Language</title>
-
-<para>
-Not all users enjoy typing in prefix query structures and numerical
-attribute values, even in a minimalistic test client. In the library
-world, the more intuitive Common Command Language (or ISO 8777) has
-enjoyed some popularity - especially before the widespread
-availability of graphical interfaces. It is still useful in
-applications where you for some reason or other need to provide a
-symbolic language for expressing boolean query structures.
-</para>
-
-<para>
-The EUROPAGATE research project working under the Libraries programme
-of the European Commission's DG XIII has, amongst other useful tools,
-implemented a general-purpose CCL parser which produces an output
-structure that can be trivially converted to the internal RPN
-representation of YAZ (The <literal>Z_RPNQuery</literal> structure).
-Since the CCL utility - along with the rest of the software
-produced by EUROPAGATE - is made freely available on a liberal license, it
-is included as a supplement to YAZ.
-</para>
-
-<sect3><title>CCL Syntax</title>
-
-<para>
-The CCL parser obeys the following grammar for the FIND argument.
-The syntax is annotated by in the lines prefixed by
-<literal>‐‐</literal>.
-</para>
-
-<screen>
-CCL-Find ::= CCL-Find Op Elements
- | Elements.
-
-Op ::= "and" | "or" | "not"
--- The above means that Elements are separated by boolean operators.
-
-Elements ::= '(' CCL-Find ')'
- | Set
- | Terms
- | Qualifiers Relation Terms
- | Qualifiers Relation '(' CCL-Find ')'
- | Qualifiers '=' string '-' string
--- Elements is either a recursive definition, a result set reference, a
--- list of terms, qualifiers followed by terms, qualifiers followed
--- by a recursive definition or qualifiers in a range (lower - upper).
-
-Set ::= 'set' = string
--- Reference to a result set
-
-Terms ::= Terms Prox Term
- | Term
--- Proximity of terms.
-
-Term ::= Term string
- | string
--- This basically means that a term may include a blank
-
-Qualifiers ::= Qualifiers ',' string
- | string
--- Qualifiers is a list of strings separated by comma
-
-Relation ::= '=' | '>=' | '<=' | '<>' | '>' | '<'
--- Relational operators. This really doesn't follow the ISO8777
--- standard.
-
-Prox ::= '%' | '!'
--- Proximity operator
-
-</screen>
-
-<para>
-The following queries are all valid:
-</para>
-
-<screen>
-dylan
-
-"bob dylan"
-
-dylan or zimmerman
-
-set=1
-
-(dylan and bob) or set=1
-
-</screen>
-<para>
-Assuming that the qualifiers <literal>ti</literal>, <literal>au</literal>
-and <literal>date</literal> are defined we may use:
-</para>
-
-<screen>
-ti=self portrait
-
-au=(bob dylan and slow train coming)
-
-date>1980 and (ti=((self portrait)))
-
-</screen>
-
-</sect3>
-<sect3><title>CCL Qualifiers</title>
-
-<para>
-Qualifiers are used to direct the search to a particular searchable
-index, such as title (ti) and author indexes (au). The CCL standard
-itself doesn't specify a particular set of qualifiers, but it does
-suggest a few short-hand notations. You can customize the CCL parser
-to support a particular set of qualifiers to relect the current target
-profile. Traditionally, a qualifier would map to a particular
-use-attribute within the BIB-1 attribute set. However, you could also
-define qualifiers that would set, for example, the
-structure-attribute.
-</para>
-
-<para>
-Consider a scenario where the target support ranked searches in the
-title-index. In this case, the user could specify
-</para>
-
-<screen>>
-ti,ranked=knuth computer
-</screen>
-<para>
-and the <literal>ranked</literal> would map to structure=free-form-text
-(4=105) and the <literal>ti</literal> would map to title (1=4).
-</para>
-
-<para>
-A "profile" with a set predefined CCL qualifiers can be read from a
-file. The YAZ client reads its CCL qualifiers from a file named
-<filename>default.bib</filename>. Each line in the file has the form:
-</para>
-
-<para>
-<replaceable>qualifier-name</replaceable>
- <replaceable>type</replaceable>=<replaceable>val</replaceable> <replaceable>type</replaceable>=<replaceable>val</replaceable> ...
-</para>
-
-<para>
-where <replaceable>qualifier-name</replaceable> is the name of the
-qualifier to be used (eg. <literal>ti</literal>),
-<replaceable>type</replaceable> is a BIB-1 category type and
-<replaceable>val</replaceable> is the corresponding BIB-1 attribute value.
-The <replaceable>type</replaceable> can be either numeric or it may be
-either <literal>u</literal> (use), <literal>r</literal> (relation),
-<literal>p</literal> (position), <literal>s</literal> (structure),
-<literal>t</literal> (truncation) or <literal>c</literal> (completeness).
-The <replaceable>qualifier-name</replaceable> <literal>term</literal> has a
-special meaning. The types and values for this definition is used when
-<emphasis>no</emphasis> qualifiers are present.
-</para>
-
-<para>
-Consider the following definition:
-</para>
-
-<screen>
-ti u=4 s=1
-au u=1 s=1
-term s=105
-</screen>
-<para>
-Two qualifiers are defined, <literal>ti</literal> and <literal>au</literal>.
-They both set the structure-attribute to phrase (1). <literal>ti</literal>
-sets the use-attribute to 4. <literal>au</literal> sets the use-attribute
-to 1. When no qualifiers are used in the query the structure-attribute is
-set to free-form-text (105).
-</para>
-
-</sect3>
-<sect3><title>CCL API</title>
-<para>
-All public definitions can be found in the header file
-<filename>ccl.h</filename>. A profile identifier is of type
-<literal>CCL_bibset</literal>. A profile must be created with the call to
-the function <function>ccl_qual_mk</function> which returns a profile
-handle of type <literal>CCL_bibset</literal>.
-</para>
-
-<para>
-To read a file containing qualifier definitions the function
-<function>ccl_qual_file</function> may be convenient. This function takes
-an already opened <literal>FILE</literal> handle pointer as argument
-along with a <literal>CCL_bibset</literal> handle.
-</para>
-
-<para>
-To parse a simple string with a FIND query use the function
-</para>
-<screen>
- struct ccl_rpn_node *ccl_find_str (CCL_bibset bibset, const char *str,
- int *error, int *pos);
-</screen>
-<para>
-which takes the CCL profile (<literal>bibset</literal>) and query
-(<literal>str</literal>) as input. Upon successful completion the RPN
-tree is returned. If an error eccur, such as a syntax error, the integer
-pointed to by <literal>error</literal> holds the error code and
-<literal>pos</literal> holds the offset inside query string in which
-the parsing failed.
-</para>
-
-<para>
-An english representation of the error may be obtained by calling
-the <literal>ccl_err_msg</literal> function. The error codes are listed in
-<filename>ccl.h</filename>.
-</para>
-
-<para>
-To convert the CCL RPN tree (type <literal>struct ccl_rpn_node *</literal>)
-to the Z_RPNQuery of YAZ the function <function>ccl_rpn_query</function>
-must be used. This function which is part of YAZ is implemented in
-<filename>yaz-ccl.c</filename>.
-After calling this function the CCL RPN tree is probably no longer
-needed. The <literal>ccl_rpn_delete</literal> destroys the CCL RPN tree.
-</para>
-
-<para>
-A CCL profile may be destroyed by calling the <function>ccl_qual_rm</function>
-function.
-</para>
-
-<para>
-The token names for the CCL operators may be changed by setting the
-globals (all type <literal>char *</literal>)
-<literal>ccl_token_and</literal>, <literal>ccl_token_or</literal>,
-<literal>ccl_token_not</literal> and <literal>ccl_token_set</literal>.
-An operator may have aliases, i.e. there may be more than one name for
-the operator. To do this, separate each alias with a space character.
-</para>
-</sect3>
-</sect2>
-</sect1>
-<sect1><title>Object Identifiers</title>
-
-<para>
-The basic YAZ representation of an OID is an array of integers,
-terminated with the value -1. The &odr; module provides two
-utility-functions to create and copy this type of data elements:
-</para>
-
-<screen>
- Odr_oid *odr_getoidbystr(ODR o, char *str);
-</screen>
-
-<para>
-Creates an OID based on a string-based representation using dots (.)
-to separate elements in the OID.
-</para>
-
-<screen>
-Odr_oid *odr_oiddup(ODR odr, Odr_oid *o);
-</screen>
-
-<para>
-Creates a copy of the OID referenced by the <emphasis>o</emphasis> parameter.
-Both functions take an &odr; stream as parameter. This stream is used to
-allocate memory for the data elements, which is released on a
-subsequent call to <function>odr_reset()</function> on that stream.
-</para>
-
-<para>
-The OID module provides a higher-level representation of the
-family of object identifers which describe the Z39.50 protocol and its
-related objects. The definition of the module interface is given in
-the <filename>oid.h</filename> file.
-</para>
-
-<para>
-The interface is mainly based on the <literal>oident</literal> structure. The
-definition of this structure looks like this:
-</para>
-
-<screen>
+ <screen>
+ CCL-Find ::= CCL-Find Op Elements
+ | Elements.
+
+ Op ::= "and" | "or" | "not"
+ -- The above means that Elements are separated by boolean operators.
+
+ Elements ::= '(' CCL-Find ')'
+ | Set
+ | Terms
+ | Qualifiers Relation Terms
+ | Qualifiers Relation '(' CCL-Find ')'
+ | Qualifiers '=' string '-' string
+ -- Elements is either a recursive definition, a result set reference, a
+ -- list of terms, qualifiers followed by terms, qualifiers followed
+ -- by a recursive definition or qualifiers in a range (lower - upper).
+
+ Set ::= 'set' = string
+ -- Reference to a result set
+
+ Terms ::= Terms Prox Term
+ | Term
+ -- Proximity of terms.
+
+ Term ::= Term string
+ | string
+ -- This basically means that a term may include a blank
+
+ Qualifiers ::= Qualifiers ',' string
+ | string
+ -- Qualifiers is a list of strings separated by comma
+
+ Relation ::= '=' | '>=' | '<=' | '<>' | '>' | '<'
+ -- Relational operators. This really doesn't follow the ISO8777
+ -- standard.
+
+ Prox ::= '%' | '!'
+ -- Proximity operator
+
+ </screen>
+
+ <para>
+ The following queries are all valid:
+ </para>
+
+ <screen>
+ dylan
+
+ "bob dylan"
+
+ dylan or zimmerman
+
+ set=1
+
+ (dylan and bob) or set=1
+
+ </screen>
+ <para>
+ Assuming that the qualifiers <literal>ti</literal>, <literal>au</literal>
+ and <literal>date</literal> are defined we may use:
+ </para>
+
+ <screen>
+ ti=self portrait
+
+ au=(bob dylan and slow train coming)
+
+ date>1980 and (ti=((self portrait)))
+
+ </screen>
+
+ </sect3>
+ <sect3><title>CCL Qualifiers</title>
+
+ <para>
+ Qualifiers are used to direct the search to a particular searchable
+ index, such as title (ti) and author indexes (au). The CCL standard
+ itself doesn't specify a particular set of qualifiers, but it does
+ suggest a few short-hand notations. You can customize the CCL parser
+ to support a particular set of qualifiers to reflect the current target
+ profile. Traditionally, a qualifier would map to a particular
+ use-attribute within the BIB-1 attribute set. However, you could also
+ define qualifiers that would set, for example, the
+ structure-attribute.
+ </para>
+
+ <para>
+ Consider a scenario where the target support ranked searches in the
+ title-index. In this case, the user could specify
+ </para>
+
+ <screen>
+ ti,ranked=knuth computer
+ </screen>
+ <para>
+ and the <literal>ranked</literal> would map to relation=relevance
+ (2=102) and the <literal>ti</literal> would map to title (1=4).
+ </para>
+
+ <para>
+ A "profile" with a set predefined CCL qualifiers can be read from a
+ file. The YAZ client reads its CCL qualifiers from a file named
+ <filename>default.bib</filename>. Each line in the file has the form:
+ </para>
+
+ <para>
+ <replaceable>qualifier-name</replaceable>
+ <replaceable>type</replaceable>=<replaceable>val</replaceable>
+ <replaceable>type</replaceable>=<replaceable>val</replaceable> ...
+ </para>
+
+ <para>
+ where <replaceable>qualifier-name</replaceable> is the name of the
+ qualifier to be used (eg. <literal>ti</literal>),
+ <replaceable>type</replaceable> is a BIB-1 category type and
+ <replaceable>val</replaceable> is the corresponding BIB-1 attribute
+ value.
+ The <replaceable>type</replaceable> can be either numeric or it may be
+ either <literal>u</literal> (use), <literal>r</literal> (relation),
+ <literal>p</literal> (position), <literal>s</literal> (structure),
+ <literal>t</literal> (truncation) or <literal>c</literal> (completeness).
+ The <replaceable>qualifier-name</replaceable> <literal>term</literal>
+ has a special meaning.
+ The types and values for this definition is used when
+ <emphasis>no</emphasis> qualifiers are present.
+ </para>
+
+ <para>
+ Consider the following definition:
+ </para>
+
+ <screen>
+ ti u=4 s=1
+ au u=1 s=1
+ term s=105
+ </screen>
+ <para>
+ Two qualifiers are defined, <literal>ti</literal> and
+ <literal>au</literal>.
+ They both set the structure-attribute to phrase (1).
+ <literal>ti</literal>
+ sets the use-attribute to 4. <literal>au</literal> sets the
+ use-attribute to 1.
+ When no qualifiers are used in the query the structure-attribute is
+ set to free-form-text (105).
+ </para>
+
+ </sect3>
+ <sect3><title>CCL API</title>
+ <para>
+ All public definitions can be found in the header file
+ <filename>ccl.h</filename>. A profile identifier is of type
+ <literal>CCL_bibset</literal>. A profile must be created with the call
+ to the function <function>ccl_qual_mk</function> which returns a profile
+ handle of type <literal>CCL_bibset</literal>.
+ </para>
+
+ <para>
+ To read a file containing qualifier definitions the function
+ <function>ccl_qual_file</function> may be convenient. This function
+ takes an already opened <literal>FILE</literal> handle pointer as
+ argument along with a <literal>CCL_bibset</literal> handle.
+ </para>
+
+ <para>
+ To parse a simple string with a FIND query use the function
+ </para>
+ <screen>
+struct ccl_rpn_node *ccl_find_str (CCL_bibset bibset, const char *str,
+ int *error, int *pos);
+ </screen>
+ <para>
+ which takes the CCL profile (<literal>bibset</literal>) and query
+ (<literal>str</literal>) as input. Upon successful completion the RPN
+ tree is returned. If an error occur, such as a syntax error, the integer
+ pointed to by <literal>error</literal> holds the error code and
+ <literal>pos</literal> holds the offset inside query string in which
+ the parsing failed.
+ </para>
+
+ <para>
+ An English representation of the error may be obtained by calling
+ the <literal>ccl_err_msg</literal> function. The error codes are
+ listed in <filename>ccl.h</filename>.
+ </para>
+
+ <para>
+ To convert the CCL RPN tree (type
+ <literal>struct ccl_rpn_node *</literal>)
+ to the Z_RPNQuery of YAZ the function <function>ccl_rpn_query</function>
+ must be used. This function which is part of YAZ is implemented in
+ <filename>yaz-ccl.c</filename>.
+ After calling this function the CCL RPN tree is probably no longer
+ needed. The <literal>ccl_rpn_delete</literal> destroys the CCL RPN tree.
+ </para>
+
+ <para>
+ A CCL profile may be destroyed by calling the
+ <function>ccl_qual_rm</function> function.
+ </para>
+
+ <para>
+ The token names for the CCL operators may be changed by setting the
+ globals (all type <literal>char *</literal>)
+ <literal>ccl_token_and</literal>, <literal>ccl_token_or</literal>,
+ <literal>ccl_token_not</literal> and <literal>ccl_token_set</literal>.
+ An operator may have aliases, i.e. there may be more than one name for
+ the operator. To do this, separate each alias with a space character.
+ </para>
+ </sect3>
+ </sect2>
+ <sect2 id="tools.cql"><title>CQL</title>
+ <para>
+ <ulink url="http://www.loc.gov/z3950/agency/zing/cql/">CQL</ulink>
+ - Common Query Language - was defined for the
+ <ulink url="http://www.loc.gov/z3950/agency/zing/srw/">SRW</ulink>
+ protocol.
+ In many ways CQL has a similar syntax to CCL.
+ The objective of CQL is different. Where CCL aims to be
+ an end-user language, CQL is <emphasis>the</emphasis> protocol
+ query language for SRW.
+ </para>
+ <tip>
+ <para>
+ If you are new to CQL, read the
+ <ulink url="http://zing.z3950.org/cql/intro.html">Gentle
+ Introduction</ulink>.
+ </para>
+ </tip>
+ <para>
+ The CQL parser in &yaz; provides the following:
+ <itemizedlist>
+ <listitem>
+ <para>
+ It parses and validates a CQL query.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ It generates a C structure that allows you to convert
+ a CQL query to some other query language, such as SQL.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ The parser converts a valid CQL query to PQF, thus providing a
+ way to use CQL for both SRW/SRU servers and Z39.50 targets at the
+ same time.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ The parser converts CQL to
+ <ulink url="http://www.loc.gov/z3950/agency/zing/cql/xcql.html">
+ XCQL</ulink>.
+ XCQL is an XML representation of CQL.
+ XCQL is part of the SRW specification. However, since SRU
+ supports CQL only, we don't expect XCQL to be widely used.
+ Furthermore, CQL has the advantage over XCQL that it is
+ easy to read.
+ </para>
+ </listitem>
+ </itemizedlist>
+ </para>
+ <sect3 id="tools.cql.parsing"><title>CQL parsing</title>
+ <para>
+ A CQL parser is represented by the <literal>CQL_parser</literal>
+ handle. Its contents should be considered &yaz; internal (private).
+ <synopsis>
+#include <yaz/cql.h>
+
+typedef struct cql_parser *CQL_parser;
+
+CQL_parser cql_parser_create(void);
+void cql_parser_destroy(CQL_parser cp);
+ </synopsis>
+ A parser is created by <function>cql_parser_create</function> and
+ is destroyed by <function>cql_parser_destroy</function>.
+ </para>
+ <para>
+ To parse a CQL query string, the following function
+ is provided:
+ <synopsis>
+int cql_parser_string(CQL_parser cp, const char *str);
+ </synopsis>
+ A CQL query is parsed by the <function>cql_parser_string</function>
+ which takes a query <parameter>str</parameter>.
+ If the query was valid (no syntax errors), then zero is returned;
+ otherwise a non-zero error code is returned.
+ </para>
+ <para>
+ <synopsis>
+int cql_parser_stream(CQL_parser cp,
+ int (*getbyte)(void *client_data),
+ void (*ungetbyte)(int b, void *client_data),
+ void *client_data);
+
+int cql_parser_stdio(CQL_parser cp, FILE *f);
+ </synopsis>
+ The functions <function>cql_parser_stream</function> and
+ <function>cql_parser_stdio</function> parses a CQL query
+ - just like <function>cql_parser_string</function>.
+ The only difference is that the CQL query can be
+ fed to the parser in different ways.
+ The <function>cql_parser_stream</function> uses a generic
+ byte stream as input. The <function>cql_parser_stdio</function>
+ uses a <literal>FILE</literal> handle which is opened for reading.
+ </para>
+ </sect3>
+
+ <sect3 id="tools.cql.tree"><title>CQL tree</title>
+ <para>
+ The the query string is validl, the CQL parser
+ generates a tree representing the structure of the
+ CQL query.
+ </para>
+ <para>
+ <synopsis>
+struct cql_node *cql_parser_result(CQL_parser cp);
+ </synopsis>
+ <function>cql_parser_result</function> returns the
+ a pointer to the root node of the resulting tree.
+ </para>
+ <para>
+ Each node in a CQL tree is represented by a
+ <literal>struct cql_node</literal>.
+ It is defined as follows:
+ <synopsis>
+#define CQL_NODE_ST 1
+#define CQL_NODE_BOOL 2
+#define CQL_NODE_MOD 3
+struct cql_node {
+ int which;
+ union {
+ struct {
+ char *index;
+ char *term;
+ char *relation;
+ struct cql_node *modifiers;
+ struct cql_node *prefixes;
+ } st;
+ struct {
+ char *value;
+ struct cql_node *left;
+ struct cql_node *right;
+ struct cql_node *modifiers;
+ struct cql_node *prefixes;
+ } boolean;
+ struct {
+ char *name;
+ char *value;
+ struct cql_node *next;
+ } mod;
+ } u;
+};
+ </synopsis>
+ There are three kinds of nodes, search term (ST), boolean (BOOL),
+ and modifier (MOD).
+ </para>
+ <para>
+ The search term node has five members:
+ <itemizedlist>
+ <listitem>
+ <para>
+ <literal>index</literal>: index for search term.
+ If an index is unspecified for a search term,
+ <literal>index</literal> will be NULL.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ <literal>term</literal>: the search term itself.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ <literal>relation</literal>: relation for search term.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ <literal>modifiers</literal>: relation modifiers for search
+ term. The <literal>modifiers</literal> is a simple linked
+ list (NULL for last entry). Each relation modifier node
+ is of type <literal>MOD</literal>.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ <literal>prefixes</literal>: index prefixes for search
+ term. The <literal>prefixes</literal> is a simple linked
+ list (NULL for last entry). Each prefix node
+ is of type <literal>MOD</literal>.
+ </para>
+ </listitem>
+ </itemizedlist>
+ </para>
+
+ <para>
+ The boolean node represents both <literal>and</literal>,
+ <literal>or</literal>, not as well as
+ proximity.
+ <itemizedlist>
+ <listitem>
+ <para>
+ <literal>left</literal> and <literal>right</literal>: left
+ - and right operand respectively.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ <literal>modifiers</literal>: proximity arguments.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ <literal>prefixes</literal>: index prefixes.
+ The <literal>prefixes</literal> is a simple linked
+ list (NULL for last entry). Each prefix node
+ is of type <literal>MOD</literal>.
+ </para>
+ </listitem>
+ </itemizedlist>
+ </para>
+
+ <para>
+ The modifier node is a "utility" node used for name-value pairs,
+ such as prefixes, proximity arguements, etc.
+ <itemizedlist>
+ <listitem>
+ <para>
+ <literal>name</literal> name of mod node.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ <literal>value</literal> value of mod node.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ <literal>next</literal>: pointer to next node which is
+ always a mod node (NULL for last entry).
+ </para>
+ </listitem>
+ </itemizedlist>
+ </para>
+
+ </sect3>
+ <sect3 id="tools.cql.pqf"><title>CQL to PQF conversion</title>
+ <para>
+ Conversion to PQF (and Z39.50 RPN) is tricky by the fact
+ that the resulting RPN depends on the Z39.50 target
+ capabilities (combinations of supported attributes).
+ In addition, the CQL and SRW operates on index prefixes
+ (URI or strings), whereas the RPN uses Object Identifiers
+ for attribute sets.
+ </para>
+ <para>
+ The CQL library of &yaz; defines a <literal>cql_transform_t</literal>
+ type. It represents a particular mapping between CQL and RPN.
+ This handle is created and destroyed by the functions:
+ <synopsis>
+cql_transform_t cql_transform_open_FILE (FILE *f);
+cql_transform_t cql_transform_open_fname(const char *fname);
+void cql_transform_close(cql_transform_t ct);
+ </synopsis>
+ The first two functions create a tranformation handle from
+ either an already open FILE or from a filename respectively.
+ </para>
+ <para>
+ The handle is destroyed by <function>cql_transform_close</function>
+ in which case no further reference of the handle is allowed.
+ </para>
+ <para>
+ When a <literal>cql_transform_t</literal> handle has been created
+ you can convert to RPN.
+ <synopsis>
+int cql_transform_buf(cql_transform_t ct,
+ struct cql_node *cn, char *out, int max);
+ </synopsis>
+ This function converts the CQL tree <literal>cn</literal>
+ using handle <literal>ct</literal>.
+ For the resulting PQF, you supply a buffer <literal>out</literal>
+ which must be able to hold at at least <literal>max</literal>
+ characters.
+ </para>
+ <para>
+ If conversion failed, <function>cql_transform_buf</function>
+ returns a non-zero error code; otherwise zero is returned
+ (conversion successful).
+ </para>
+ <para>
+ If you wish to be able to produce a PQF result in a different
+ way, there are two alternatives.
+ <synopsis>
+void cql_transform_pr(cql_transform_t ct,
+ struct cql_node *cn,
+ void (*pr)(const char *buf, void *client_data),
+ void *client_data);
+
+int cql_transform_FILE(cql_transform_t ct,
+ struct cql_node *cn, FILE *f);
+ </synopsis>
+ The former function produces output to a user-defined
+ output stream. The latter writes the result to an already
+ open <literal>FILE</literal>.
+ </para>
+ </sect3>
+ <sect3 id="tools.cql.map">
+ <title>Specification of CQL to RPN mapping</title>
+ <para>
+ The file supplied to functions
+ <function>cql_transform_open_FILE</function>,
+ <function>cql_transform_open_fname</function> follows
+ a structure found in many Unix utilities.
+ It consists of mapping specifications - one per line.
+ Lines starting with <literal>#</literal> are ignored (comments).
+ </para>
+ <para>
+ Each line is of the form
+ <literallayout>
+ <replaceable>CQL pattern</replaceable><literal> = </literal> <replaceable> RPN equivalent</replaceable>
+ </literallayout>
+ </para>
+ <para>
+ An RPN pattern is a simple attribute list. Each attribute pair
+ takes the form:
+ <literallayout>
+ [<replaceable>set</replaceable>] <replaceable>type</replaceable><literal>=</literal><replaceable>value</replaceable>
+ </literallayout>
+ The attribute <replaceable>set</replaceable> is optional.
+ The <replaceable>type</replaceable> is the attribute type,
+ <replaceable>value</replaceable> the attribute value.
+ </para>
+ <para>
+ The following CQL patterns are recognized:
+ <variablelist>
+ <varlistentry><term>
+ <literal>qualifier.</literal><replaceable>set</replaceable><literal>.</literal><replaceable>name</replaceable>
+ </term>
+ <listitem>
+ <para>
+ This pattern is invoked when a CQL qualifier, such as
+ dc.title is converted. <replaceable>set</replaceable>
+ and <replaceable>name</replaceable> is the index set and qualifier
+ name respectively.
+ Typically, the RPN specifies an equivalent use attribute.
+ </para>
+ <para>
+ For terms not bound by a qualifier the pattern
+ <literal>qualifier.srw.serverChoice</literal> is used.
+ Here, the prefix <literal>srw</literal> is defined as
+ <literal>http://www.loc.gov/zing/cql/srw-indexes/v1.0/</literal>.
+ If this pattern is not defined, the mapping will fail.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry><term>
+ <literal>relation.</literal><replaceable>relation</replaceable>
+ </term>
+ <listitem>
+ <para>
+ This pattern specifies how a CQL relation is mapped to RPN.
+ <replaceable>pattern</replaceable> is name of relation
+ operator. Since <literal>=</literal> is used as
+ separator between CQL pattern and RPN, CQL relations
+ including <literal>=</literal> cannot be
+ used directly. To avoid a conflict, the names
+ <literal>ge</literal>,
+ <literal>eq</literal>,
+ <literal>le</literal>,
+ must be used for CQL operators, greater-than-or-equal,
+ equal, less-than-or-equal respectively.
+ The RPN pattern is supposed to include a relation attribute.
+ </para>
+ <para>
+ For terms not bound by a relation, the pattern
+ <literal>relation.scr</literal> is used. If the pattern
+ is not defined, the mapping will fail.
+ </para>
+ <para>
+ The special pattern, <literal>relation.*</literal> is used
+ when no other relation pattern is matched.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry><term>
+ <literal>relationModifier.</literal><replaceable>mod</replaceable>
+ </term>
+ <listitem>
+ <para>
+ This pattern specifies how a CQL relation modifier is mapped to RPN.
+ The RPN pattern is usually a relation attribute.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry><term>
+ <literal>structure.</literal><replaceable>type</replaceable>
+ </term>
+ <listitem>
+ <para>
+ This pattern specifies how a CQL structure is mapped to RPN.
+ Note that this CQL pattern is somewhat to similar to
+ CQL pattern <literal>relation</literal>.
+ The <replaceable>type</replaceable> is a CQL relation.
+ </para>
+ <para>
+ The pattern, <literal>structure.*</literal> is used
+ when no other structure pattern is matched.
+ Usually, the RPN equivalent specifies a structure attribute.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry><term>
+ <literal>position.</literal><replaceable>type</replaceable>
+ </term>
+ <listitem>
+ <para>
+ This pattern specifies how the anchor (position) of
+ CQL is mapped to RPN.
+ The <replaceable>type</replaceable> is one
+ of <literal>first</literal>, <literal>any</literal>,
+ <literal>last</literal>, <literal>firstAndLast</literal>.
+ </para>
+ <para>
+ The pattern, <literal>position.*</literal> is used
+ when no other position pattern is matched.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry><term>
+ <literal>set.</literal><replaceable>prefix</replaceable>
+ </term>
+ <listitem>
+ <para>
+ This specification defines a CQL index set for a given prefix.
+ The value on the right hand side is the URI for the set -
+ <emphasis>not</emphasis> RPN. All prefixes used in
+ qualifier patterns must be defined this way.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </para>
+ <example><title>Small CQL to RPN mapping file</title>
+ <para>
+ This small file defines two index sets, three qualifiers and three
+ relations, a position pattern and a default structure.
+ </para>
+ <programlisting><![CDATA[
+ set.srw = http://www.loc.gov/zing/cql/srw-indexes/v1.0/
+ set.dc = http://www.loc.gov/zing/cql/dc-indexes/v1.0/
+
+ qualifier.srw.serverChoice = 1=1016
+ qualifier.dc.title = 1=4
+ qualifier.dc.subject = 1=21
+
+ relation.< = 2=1
+ relation.eq = 2=3
+ relation.scr = 2=3
+
+ position.any = 3=3 6=1
+
+ structure.* = 4=1
+]]>
+ </programlisting>
+ <para>
+ With the mappings above, the CQL query
+ <screen>
+ computer
+ </screen>
+ is converted to the PQF:
+ <screen>
+ @attr 1=1016 @attr 2=3 @attr 4=1 @attr 3=3 @attr 6=1 "computer"
+ </screen>
+ by rules <literal>qualifier.srw.serverChoice</literal>,
+ <literal>relation.scr</literal>, <literal>structure.*</literal>,
+ <literal>position.any</literal>.
+ </para>
+ <para>
+ CQL query
+ <screen>
+ computer^
+ </screen>
+ is rejected, since <literal>position.right</literal> is
+ undefined.
+ </para>
+ <para>
+ CQL query
+ <screen>
+ >my = "http://www.loc.gov/zing/cql/dc-indexes/v1.0/" my.title = x
+ </screen>
+ is converted to
+ <screen>
+ @attr 1=4 @attr 2=3 @attr 4=1 @attr 3=3 @attr 6=1 "x"
+ </screen>
+ </para>
+ </example>
+ </sect3>
+ <sect3 id="tools.cql.xcql"><title>CQL to XCQL conversion</title>
+ <para>
+ Conversion from CQL to XCQL is trivial and does not
+ require a mapping to be defined.
+ There three functions to choose from depending on the
+ way you wish to store the resulting output (XML buffer
+ containing XCQL).
+ <synopsis>
+int cql_to_xml_buf(struct cql_node *cn, char *out, int max);
+void cql_to_xml(struct cql_node *cn,
+ void (*pr)(const char *buf, void *client_data),
+ void *client_data);
+void cql_to_xml_stdio(struct cql_node *cn, FILE *f);
+ </synopsis>
+ Function <function>cql_to_xml_buf</function> converts
+ to XCQL and stores result in a user supplied buffer of a given
+ max size.
+ </para>
+ <para>
+ <function>cql_to_xml</function> writes the result in
+ a user defined output stream.
+ <function>cql_to_xml_stdio</function> writes to a
+ a file.
+ </para>
+ </sect3>
+ </sect2>
+ </sect1>
+ <sect1 id="tools.oid"><title>Object Identifiers</title>
+
+ <para>
+ The basic YAZ representation of an OID is an array of integers,
+ terminated with the value -1. The &odr; module provides two
+ utility-functions to create and copy this type of data elements:
+ </para>
+
+ <screen>
+ Odr_oid *odr_getoidbystr(ODR o, char *str);
+ </screen>
+
+ <para>
+ Creates an OID based on a string-based representation using dots (.)
+ to separate elements in the OID.
+ </para>
+
+ <screen>
+ Odr_oid *odr_oiddup(ODR odr, Odr_oid *o);
+ </screen>
+
+ <para>
+ Creates a copy of the OID referenced by the <emphasis>o</emphasis>
+ parameter.
+ Both functions take an &odr; stream as parameter. This stream is used to
+ allocate memory for the data elements, which is released on a
+ subsequent call to <function>odr_reset()</function> on that stream.
+ </para>
+
+ <para>
+ The OID module provides a higher-level representation of the
+ family of object identifiers which describe the Z39.50 protocol and its
+ related objects. The definition of the module interface is given in
+ the <filename>oid.h</filename> file.
+ </para>
+
+ <para>
+ The interface is mainly based on the <literal>oident</literal> structure.
+ The definition of this structure looks like this:
+ </para>
+
+ <screen>