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FWEB version 1.62 (September 25, 1998)
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Based on version 0.5 of S. Levy's CWEB [copyright (C) 1987 Princeton University]
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@x-----------------------------------------------------------------------------
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@* DATA STRUCTURES EXCLUSIVE to WEAVE.
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As explained in \.{common.web}, the field of a |name_info| structure that
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contains the |rlink| of a module name is used for a completely different
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purpose in the case of identifiers. It is then called the |ilk| of the
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identifier, and it is used to distinguish between various types of
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identifiers, as follows:
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{\narrower\narrower\everypar={\noindent\hang}
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|normal| identifiers are part of the \cee\ program; they
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will appear in \It{italic type}.
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|roman| identifiers are index entries that appear after
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\.{@@\^} in the \.{WEB} file.
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|wildcard| identifiers are index entries that appear after
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\.{@@9} in the \.{WEB} file; they will appear in a format controlled by the
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user-defined macro~\.{\\9}.
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|typewriter| identifiers are index entries that appear after
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\.{@@.} in the \.{WEB} file; they will appear in \.{typewriter type}.
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|do_like| \dots\ identifiers are reserved words whose |ilk| explains how
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they are to be treated when code is being formatted.
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@d normal 0 /* ordinary identifiers have |normal| ilk */
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@d roman 1 /* normal index entries have |roman| ilk */
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@d wildcard 2 /* user-formatted index entries have |wildcard| ilk */
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@d typewriter 3 /* `typewriter type' entries have |typewriter| ilk */
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@d is_reserved(a) (a->ilk>typewriter) /* tells if a name is a reserved word */
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@ We keep track of the current module number in |module_count|, which is
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the total number of modules that have started. Modules which have been
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altered by a change file entry have their |chngd_module| flag turned on
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during the first phase.
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EXTERN boolean change_exists; /* has any module changed? */
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@ The other large memory area in \WEAVE\ keeps the cross-reference data.
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All uses of the name~|p| are recorded in a linked list beginning at
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|p->xref|, which points into the |xmem| array. The elements of |xmem| are
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structures consisting of an integer~|num| and a pointer~|xlink| to
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another element of |xmem|. If |x=p->xref| is a pointer into |xmem|, the
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value of |x->num| is either a module number where |p|~is used, or it is
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|def_flag| plus a module number where |p|~is defined; and |x->xlink| points
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to the next such cross-reference for~|p|, if any. This list of
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cross-references is in decreasing order by module number. The next unused
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slot in |xmem| is |xref_ptr|.
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The global variable |xref_switch| is set either to |def_flag| or to zero,
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depending on whether the next cross-reference to an identifier is to be
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underlined or not in the index. This switch is set to |def_flag| when
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\.{@@\_}, \.{@@[}, \.{@@]},\.{@@d}, \.{@@m}, or \.{@@f} is scanned, and it
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is cleared to zero when the next identifier or index entry cross-reference
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has been made. Similarly, the global variable |mod_xref_switch| is either
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|def_flag| or zero, depending on whether a module name is being defined or
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@d append_xref(c) if (xref_ptr==xmem_end)
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OVERFLW("cross-references",ABBREV(max_refs));
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xref_ptr->Language = (boolean) language;
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typedef struct xref_info0
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sixteen_bits num; /* module number plus zero or |def_flag| */
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struct xref_info0 HUGE *xlink; /* pointer to the previous
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boolean Language; /* Language in force for this module. */
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typedef xref_info HUGE *xref_pointer;
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typedef ASCII HUGE *XREF_POINTER; /* For assignments like |name_dir->xref =
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(XREF_POINTER)xref_ptr|. See the comment
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immediately below about~|xref|. */
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@ The integer |def_flag| is added to a module number when that module is
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For variable names, a different approach is taken. If a name (especially a
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function name) is preceded by~\.{@@[}, the switch |defd_switch| is set to
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|YES|. Then when |new_xref| is called, the module number of that name is
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entered into the |defined_in| field.
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@d def_flag ID_FLAG /* must be strictly larger than |max_modules| */
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@d xref equiv_or_xref /* The trouble with this is that |xref| is a
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|xref_pointer| whereas |equiv_or_xref| is |ASCII|. This means that
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lots of casting needs to be done to keep the compiler happy. Hence
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the previous |typedef|. */
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IN_COMMON BUF_SIZE max_modules; /* Size allocated in \.{common.web}. */
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EXTERN BUF_SIZE max_refs;
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EXTERN xref_info HUGE *xmem; /* contains cross-reference information */
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EXTERN xref_pointer xmem_end;
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EXTERN xref_pointer xref_ptr; /* the largest occupied position in |xmem| */
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EXTERN sixteen_bits xref_switch,mod_xref_switch; // either zero or |def_flag|.
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EXTERN boolean defd_switch; // Set by `\.{@@[}'.
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EXTERN NAME_TYPE defd_type SET(NEVER_DEFINED);
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EXTERN boolean typd_switch; // Set by `\.{@@]}'.
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EXTERN boolean index_short; // Set by `\.{@@+}'.
added
removed
Web/xrefs.hweb
