This is a page from DPANS'94, the Draft Proposal on ANS Forth 1994.
There are just additional cross-references to reserved words on a seperate page.
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11. The optional File-Access word set

See: A.11 The optional File-Access word set


11.1 Introduction

These words provide access to mass storage in the form of files under the following assumptions:


11.2 Additional terms

file-access method:
A permissible means of accessing a file, such as read/write or read only.
file position:
The character offset from the start of the file.
input file:
The file, containing a sequence of lines, that is the input source.

11.3 Additional usage requirements


11.3.1 Data types

Append table 11.1 to table 3.1.

Table 11.1 - Data types

Symbol  Data type               Size on stack
------  ---------               -------------
ior     I/O results             1 cell
fam     file access method      1 cell
fileid  file identifiers        1 cell


11.3.1.1 File identifiers

File identifiers are implementation-dependent single-cell values that are passed to file operators to designate specific files. Opening a file assigns a file identifier, which remains valid until closed.


11.3.1.2 I/O results

I/O results are single-cell numbers indicating the result of I/O operations. A value of zero indicates that the I/O operation completed successfully; other values and their meanings are implementation-defined. Reaching the end of a file shall be reported as zero.

An I/O exception in the execution of a File-Access word that can return an I/O result shall not cause a THROW; exception indications are returned in the ior.


11.3.1.3 File access methods

File access methods are implementation-defined single-cell values.


11.3.1.4 File names

A character string containing the name of the file. The file name may include an implementation-dependent path name. The format of file names is implementation defined.


11.3.2 Blocks in files

If the File-Access word set is implemented, the Block word set shall be implemented.

Blocks may, but need not, reside in files. When they do:

See: A.11.3.2 Blocks in files


11.3.3 Environmental queries

Append table 11.2 to table 3.5.

See: 3.2.6 Environmental queries

Table 11.2 - Environmental query strings

String         Value data type   Constant?  Meaning
------         ---------------   ---------  -------
FILE            flag             no         file word set present
FILE-EXT        flag             no         file extensions word set present


11.3.4 Input source

The File-Access word set creates another input source for the text interpreter. When the input source is a text file, BLK shall contain zero, SOURCE-ID shall contain the fileid of that text file, and the input buffer shall contain one line of the text file.

Input with INCLUDED, INCLUDE-FILE, LOAD and EVALUATE shall be nestable in any order to at least eight levels.

A program that uses more than eight levels of input-file nesting has an environmental dependency.

See: 3.3.3.5 Input buffers, 9. Optional Exception word set.


11.3.5 Other transient regions

The list of words using memory in transient regions is extended to include 11.6.1.2165 S".

See: 3.3.3.6 Other transient regions


11.3.6 Parsing

When parsing from a text file using a space delimiter, control characters shall be treated the same as the space character.

Lines of at least 128 characters shall be supported. A program that requires lines of more than 128 characters has an environmental dependency.

A program may reposition the parse area within the input buffer by manipulating the contents of >IN. More extensive repositioning can be accomplished using SAVE-INPUT and RESTORE-INPUT.

See: 3.4.1 Parsing


11.4 Additional documentation requirements


11.4.1 System documentation


11.4.1.1 Implementation-defined options


11.4.1.2 Ambiguous conditions


11.4.1.3 Other system documentation


11.4.2 Program documentation


11.4.2.1 Environmental dependencies


11.4.2.2 Other program documentation


11.5 Compliance and labeling


11.5.1 ANS Forth systems

The phrase Providing the File Access word set shall be appended to the label of any Standard System that provides all of the File Access word set.

The phrase Providing name(s) from the File Access Extensions word set shall be appended to the label of any Standard System that provides portions of the File Access Extensions word set.

The phrase Providing the File Access Extensions word set shall be appended to the label of any Standard System that provides all of the File Access and File Access Extensions word sets.


11.5.2 ANS Forth programs

The phrase Requiring the File Access word set shall be appended to the label of Standard Programs that require the system to provide the File Access word set.

The phrase Requiring name(s) from the File Access Extensions word set shall be appended to the label of Standard Programs that require the system to provide portions of the File Access Extensions word set.

The phrase Requiring the File Access Extensions word set shall be appended to the label of Standard Programs that require the system to provide all of the File Access and File Access Extensions word sets.


11.6 Glossary


11.6.1 File Access words


11.6.1.0080 (
paren FILE
        ( "ccc<paren>" -- )

Extend the semantics of 6.1.0080 ( to include:

When parsing from a text file, if the end of the parse area is reached before a right parenthesis is found, refill the input buffer from the next line of the file, set >IN to zero, and resume parsing, repeating this process until either a right parenthesis is found or the end of the file is reached.


11.6.1.0765 BIN
FILE
        ( fam1 -- fam2 )

Modify the implementation-defined file access method fam1 to additionally select a binary, i.e., not line oriented, file access method, giving access method fam2.

See: A.11.6.1.0765 BIN , 11.6.1.2054 R/O , 11.6.1.2056 R/W , 11.6.1.2425 W/O


11.6.1.0900 CLOSE-FILE
FILE
        ( fileid -- ior )

Close the file identified by fileid. ior is the implementation-defined I/O result code.


11.6.1.1010 CREATE-FILE
FILE
        ( c-addr u fam -- fileid ior )

Create the file named in the character string specified by c-addr and u, and open it with file access method fam. The meaning of values of fam is implementation defined. If a file with the same name already exists, recreate it as an empty file.

If the file was successfully created and opened, ior is zero, fileid is its identifier, and the file has been positioned to the start of the file.

Otherwise, ior is the implementation-defined I/O result code and fileid is undefined.

See: A.11.6.1.1010 CREATE-FILE


11.6.1.1190 DELETE-FILE
FILE
        ( c-addr u -- ior )

Delete the file named in the character string specified by c-addr u. ior is the implementation-defined I/O result code.


11.6.1.1520 FILE-POSITION
FILE
        ( fileid -- ud ior )

ud is the current file position for the file identified by fileid. ior is the implementation-defined I/O result code. ud is undefined if ior is non-zero.


11.6.1.1522 FILE-SIZE
FILE
        ( fileid -- ud ior )

ud is the size, in characters, of the file identified by fileid. ior is the implementation-defined I/O result code. This operation does not affect the value returned by FILE-POSITION. ud is undefined if ior is non-zero.


11.6.1.1717 INCLUDE-FILE
FILE
        ( i*x fileid -- j*x )

Remove fileid from the stack. Save the current input source specification, including the current value of SOURCE-ID. Store fileid in SOURCE-ID. Make the file specified by fileid the input source. Store zero in BLK. Other stack effects are due to the words included.

Repeat until end of file: read a line from the file, fill the input buffer from the contents of that line, set >IN to zero, and interpret.

Text interpretation begins at the file position where the next file read would occur.

When the end of the file is reached, close the file and restore the input source specification to its saved value.

An ambiguous condition exists if fileid is invalid, if there is an I/O exception reading fileid, or if an I/O exception occurs while closing fileid. When an ambiguous condition exists, the status (open or closed) of any files that were being interpreted is implementation-defined.

See: 11.3.4 Input source, A.11.6.1.1717 INCLUDE-FILE


11.6.1.1718 INCLUDED
FILE
        ( i*x c-addr u -- j*x )

Remove c-addr u from the stack. Save the current input source specification, including the current value of SOURCE-ID. Open the file specified by c-addr u, store the resulting fileid in SOURCE-ID, and make it the input source. Store zero in BLK. Other stack effects are due to the words included.

Repeat until end of file: read a line from the file, fill the input buffer from the contents of that line, set >IN to zero, and interpret.

Text interpretation begins at the file position where the next file read would occur.

When the end of the file is reached, close the file and restore the input source specification to its saved value.

An ambiguous condition exists if the named file can not be opened, if an I/O exception occurs reading the file, or if an I/O exception occurs while closing the file. When an ambiguous condition exists, the status (open or closed) of any files that were being interpreted is implementation-defined.

See: A.11.6.1.1718 INCLUDED , R.11.6.1.1718 INCLUDE , 11.6.1.1717 INCLUDE-FILE


11.6.1.1970 OPEN-FILE
FILE
        ( c-addr u fam -- fileid ior )

Open the file named in the character string specified by c-addr u, with file access method indicated by fam. The meaning of values of fam is implementation defined.

If the file is successfully opened, ior is zero, fileid is its identifier, and the file has been positioned to the start of the file.

Otherwise, ior is the implementation-defined I/O result code and fileid is undefined.

See: A.11.6.1.1970 OPEN-FILE


11.6.1.2054 R/O
r-o FILE
        ( -- fam )

fam is the implementation-defined value for selecting the read only file access method.

See: 11.6.1.1010 CREATE-FILE , 11.6.1.1970 OPEN-FILE


11.6.1.2056 R/W
r-w FILE
        ( -- fam )

fam is the implementation-defined value for selecting the read/write file access method.

See: 11.6.1.1010 CREATE-FILE , 11.6.1.1970 OPEN-FILE


11.6.1.2080 READ-FILE
FILE
        ( c-addr u1 fileid -- u2 ior )

Read u1 consecutive characters to c-addr from the current position of the file identified by fileid.

If u1 characters are read without an exception, ior is zero and u2 is equal to u1.

If the end of the file is reached before u1 characters are read, ior is zero and u2 is the number of characters actually read.

If the operation is initiated when the value returned by FILE-POSITION is equal to the value returned by FILE-SIZE for the file identified by fileid, ior is zero and u2 is zero.

If an exception occurs, ior is the implementation-defined I/O result code, and u2 is the number of characters transferred to c-addr without an exception.

An ambiguous condition exists if the operation is initiated when the value returned by FILE-POSITION is greater than the value returned by FILE-SIZE for the file identified by fileid, or if the requested operation attempts to read portions of the file not written.

At the conclusion of the operation, FILE-POSITION returns the next file position after the last character read.

See: A.11.6.1.2080 READ-FILE


11.6.1.2090 READ-LINE
FILE
        ( c-addr u1 fileid -- u2 flag ior )

Read the next line from the file specified by fileid into memory at the address c-addr. At most u1 characters are read. Up to two implementation-defined line-terminating characters may be read into memory at the end of the line, but are not included in the count u2. The line buffer provided by c-addr should be at least u1+2 characters long.

If the operation succeeded, flag is true and ior is zero. If a line terminator was received before u1 characters were read, then u2 is the number of characters, not including the line terminator, actually read (0 <= u2 <= u1). When u1 = u2, the line terminator has yet to be reached.

If the operation is initiated when the value returned by FILE-POSITION is equal to the value returned by FILE-SIZE for the file identified by fileid, flag is false, ior is zero, and u2 is zero. If ior is non-zero, an exception occurred during the operation and ior is the implementation-defined I/O result code.

An ambiguous condition exists if the operation is initiated when the value returned by FILE-POSITION is greater than the value returned by FILE-SIZE for the file identified by fileid, or if the requested operation attempts to read portions of the file not written.

At the conclusion of the operation, FILE-POSITION returns the next file position after the last character read.

See: A.11.6.1.2090 READ-LINE , RFI 0001.


11.6.1.2142 REPOSITION-FILE
FILE
        ( ud fileid -- ior )

Reposition the file identified by fileid to ud. ior is the implementation-defined I/O result code. An ambiguous condition exists if the file is positioned outside the file boundaries.

At the conclusion of the operation, FILE-POSITION returns the value ud.


11.6.1.2147 RESIZE-FILE
FILE
        ( ud fileid -- ior )

Set the size of the file identified by fileid to ud. ior is the implementation-defined I/O result code.

If the resultant file is larger than the file before the operation, the portion of the file added as a result of the operation might not have been written.

At the conclusion of the operation, FILE-SIZE returns the value ud and FILE-POSITION returns an unspecified value.

See: 11.6.1.2080 READ-FILE , 11.6.1.2090 READ-LINE


11.6.1.2165 S"
s-quote FILE

Extend the semantics of 6.1.2165 S" to be:

        Interpretation: ( "ccc<quote>" -- c-addr u )

Parse ccc delimited by " (double quote). Store the resulting string c-addr u at a temporary location. The maximum length of the temporary buffer is implementation-dependent but shall be no less than 80 characters. Subsequent uses of S" may overwrite the temporary buffer. At least one such buffer shall be provided.

        Compilation: ( "ccc<quote>" -- )

Parse ccc delimited by " (double quote). Append the run-time semantics given below to the current definition.

        Run-time: ( -- c-addr u )

Return c-addr and u that describe a string consisting of the characters ccc.

See: 3.4.1 Parsing, 6.2.0855 C" , A.11.6.1.2165 S" , 11.3.5 Other transient regions.


11.6.1.2218 SOURCE-ID
source-i-d FILE
        ( -- 0 | -1 | fileid )

Extend 6.2.2218 SOURCE-ID to include text-file input as follows:

SOURCE-ID       Input source
---------       ------------
fileid          Text file fileid
-1              String (via EVALUATE)
0               User input device

An ambiguous condition exists if SOURCE-ID is used when BLK contains a non-zero value.


11.6.1.2425 W/O
w-o FILE
        ( -- fam )

fam is the implementation-defined value for selecting the write only file access method.

See: 11.6.1.1010 CREATE-FILE , 11.6.1.1970 OPEN-FILE


11.6.1.2480 WRITE-FILE
FILE
        ( c-addr u fileid -- ior )

Write u characters from c-addr to the file identified by fileid starting at its current position. ior is the implementation-defined I/O result code.

At the conclusion of the operation, FILE-POSITION returns the next file position after the last character written to the file, and FILE-SIZE returns a value greater than or equal to the value returned by FILE-POSITION.

See: 11.6.1.2080 READ-FILE , 11.6.1.2090 READ-LINE


11.6.1.2485 WRITE-LINE
FILE
        ( c-addr u fileid -- ior )

Write u characters from c-addr followed by the implementation-dependent line terminator to the file identified by fileid starting at its current position. ior is the implementation-defined I/O result code.

At the conclusion of the operation, FILE-POSITION returns the next file position after the last character written to the file, and FILE-SIZE returns a value greater than or equal to the value returned by FILE-POSITION.

See: 11.6.1.2080 READ-FILE , 11.6.1.2090 READ-LINE


11.6.2 File-Access extension words


11.6.2.1524 FILE-STATUS
FILE EXT
        ( c-addr u -- x ior )

Return the status of the file identified by the character string c-addr u. If the file exists, ior is zero; otherwise ior is the implementation-defined I/O result code. x contains implementation-defined information about the file.


11.6.2.1560 FLUSH-FILE
FILE EXT
        ( fileid -- ior )

Attempt to force any buffered information written to the file referred to by fileid to be written to mass storage, and the size information for the file to be recorded in the storage directory if changed. If the operation is successful, ior is zero. Otherwise, it is an implementation-defined I/O result code.


11.6.2.2125 REFILL
FILE EXT
        ( -- flag )

Extend the execution semantics of 6.2.2125 REFILL with the following:

When the input source is a text file, attempt to read the next line from the text-input file. If successful, make the result the current input buffer, set >IN to zero, and return true. Otherwise return false.

See: 7.6.2.2125 REFILL


11.6.2.2130 RENAME-FILE
FILE EXT
        ( c-addr1 u1 c-addr2 u2 -- ior )

Rename the file named by the character string c-addr1 u1 to the name in the character string c-addr2 u2. ior is the implementation-defined I/O result code.


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