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source_read(+SourcePos, -NextPos, -Kind, -SourceTerm)

Read the next term from an open ECLiPSe source file

SourcePos: Source position handle
NextPos: Source position handle
Kind: kind of source term (atom)
SourceTerm: a source_term structure

Description

This reads the next source term from a source file previously opened with source_open/3. The term at the current source position SourcePos is read, and the next source position is returned for use in subsequent source_read/4 invocations (it is not possible to read twice from the same source position!).

The term that has been read is classified into one of the following categories (Kind):

handled_directive: A directive (a term with functor :-/1) which has already been handled (interpreted by source_read/3). Such directives are: module/1,3, local/1, export/1, reexport/1, use_module/1, op/3, include/1, ./2
directive: A directive (a term with functor :-/1) which has not been handled (ignored by source_read/3)
query: A query (a term with functor ?-/1)
var: A term consisting of only a variable (very likely an error)
clause: Any other term (a syntactically valid clause)
comment: Spacing, layout and comments between source terms (only when keep_comments option is in effect)
end: The end of the (top-level) source file

The information about the source term itself is returned as a structure

    :- export struct(source_term(
	term,		% the read term itself
	vars,		% list of [VarName|Var] pairs (as in readvar/3)
	...
    )).

For category 'comment', the term is a string containing the comment. For category 'end', the term is the atom end_of_file. In both these cases, vars is the empty list.

Notes on module handling: When source_read/3 encounters a module-directive (which is a handled_directive), the corresponding module is implicitly created (unless it exists already, in which case it is either reused or erased and re-created, depending on the setting of the recreate_modules option), and that module becomes the context module for any subsequently read clauses or directives. By default, source_close/2 removes these modules again in order to restore the original state.

source_read(+SourcePos, -NextPos, -Kind, -SourceTerm)

Description

See Also