Records are addressed by their offset in the table (file). As records
have generally non-fixed length, searching is often required. The
predicates below allow for finding records in the file.
- get_table_attribute(+Handle,
+Attribute, -Value)
- Fetch attributes of the table. Defined attributes:
file | Unify value with the name of the file
with which the table is associated. |
field(N) | Unify value with
declaration of n-th (1-based) field. |
field_separator | Unify value with the field
separator character. |
record_separator | Unify value with the
record separator character. |
key_field | Unify value with the 1-based
index of the field that is sorted or fails if the table contains no
sorted fields. |
field_count | Unify value with the total
number of columns in the table. |
size | Unify value with the number of
characters in the table-file, not the number of records. |
window | Unify value with a term Start
- Size, indicating the properties of the current
window. |
- table_window(+Handle,
+Start, +Size)
- If only part of the file represents the table, this call may be used to
define a window on the file. Start defines the start of the
window relative to the start of the file. Size is the size in
characters. Skipping a header is one of the possible purposes for this
call.
- table_start_of_record(+Handle,
+From, +To, -Start)
- Enumerates (on backtracking) the start of records in the table in the
region [From, To). Together with read_table_record/4,
this may be used to read the table's data.
- table_previous_record(+Handle,
+Here, -Previous)
- If Here is the start of a record, find the start of the
record before it. If Here points at an arbitrary location in
a record, the start of this record will be returned.
