pfe-dstrings-ext
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## Name

pfe-dstrings-ext ? Dynamic-Strings extension

## Synopsis

`EMPTY$ ( $: -- empty$ ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`\n$ ( $: -- newline$ ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`(M!) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`PARSE>S ( [ccc&lt;char&gt;] char -- addr len ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`S` ( [ccc&lt;`&gt;] -- addr len ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`M,S ( addr len -- addr' len ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`MCOUNT@ ( msa -- count ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`MCOUNT! ( count msa -- ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`MCOUNT ( msa -- body.addr count ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`-MCOUNT ( addr len -- msa ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`($: ?=>? (` | `)`; | ?

`[FORTH]`;
?

`0STRINGS ( -- ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$GARBAGE? ( -- flag ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$GC-OFF ( -- ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$GC-ON ( -- ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$GC-LOCK@ ( -- flag ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$GC-LOCK! ( flag -- ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$UNUSED ( -- u ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`COLLECT-$GARBAGE ( -- collected-flag ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`MAKE-$SPACE ( size #frames -- addr ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`/$BUF ( -- u ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`MAX-#$FRAMES ( -- u ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$! ( $var.dfa $: a$ -- ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$@ ( $var.pfa -- $: a$ ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`(M$:) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$" ( [ccc&lt;"&gt;] -- $: str ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$` ( [ccc&lt;`&gt;] -- $: str ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$VARIABLE ( "name" -- ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`PARSE>$ ( [ccc&lt;char&gt;] char -- $: ccc$ ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$. ( $: a$ -- ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$2DROP ( $: a$ b$ -- ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$2DUP ( $: a$ b$ -- a$ b$ a$ b$ ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$DEPTH ( -- n ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$DROP ( $: a$ -- ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$DUP ( $: a$ -- a$ a$ ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$NIP ($: a$ b$ -- b$ ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$OVER ( $: a$ b$ -- a$ b$ a$ ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$PICK ( u $: au$ ... a0$ -- au$ ... a0$ au$ ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$SWAP ( $: a$ b$ -- b$ a$ ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$EXCHANGE ( i j -- ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$S> ( $: a$ -- S: a.s ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$,S ( $: a$ -- S: a.s ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$S@ ( $: a$ -- a$ S: a.s ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$TUCK ($: a$ b$ -- b$ a$ b$ ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$TYPE ($: a$ -- ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`>$S-COPY ( a.s -- $: a$ ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`>$S ( a.s -- $: a$ ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$+ ($: a$ -- ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`S+ ( a.s -- ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`PARSE-S+ ( [ccc&lt;char&gt;] char -- ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`ENDCAT ( -- $: cat$ | empty$ ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$+" ( [ccc&lt;quote&gt;] -- ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$+` ( [ccc&lt;backtick&gt;] -- ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`#$ARGS ( -- u ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$ARGS{ ( arg1'$ ... argN'$ "arg1 ... argN &lt;}&gt;" -- ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$FRAME ( u -- ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$FRAME-DEPTH ( -- u ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`DROP-$FRAME ($: frame*$ i*$ -- i*s ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`FIND-$ARG ( s -- u true | false ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`TH-$ARG ( u -- $: arg$ ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`(DROP-$FRAME) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$POP ( $: a$ -- s: a$) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$PUSH-EXT ( a$ -- $: a$ ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$BREAKP@ ( -- $stack.break.addr ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$BUFP@ ( -- $buffer.addr ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$FBREAKP@ ( -- frame.stack.break.addr ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$FSP@ ( -- frame.stack.top.addr ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$FSP0@ ( -- initial.frame.stack.top.addr ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$SP@ ( -- string.stack.top.addr ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`$SP0@ ( -- initial.string.stack.top.addr ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`/$FRAME-ITEM ?=>? (` | `)`; | ?

`[FORTH]`;
?

`/$FRAME-STACK ?=>? (` | `)`; | ?

`[FORTH]`;
?

`/$SPACE-HEADER ( -- $space.header.size ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`0$SPACE ( $space.addr -- ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`CAT$P@ ( -- cat$.msa | 0 ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

`IN-$BUFFER? ( msa -- flag ) ?=>? (` | `)`; | ?

`[FORTH]`;
?

## Description

EMPTY$ ( $: -- empty$ ) => [FORTH]

Push the MSA of a fixed, external representation of the empty string onto the string stack. "empty-string"

\n$ ( $: -- newline$ ) => [FORTH]

Push the MSA of a fixed, external string whose body is the Unix newline character onto the string stack. "newline-string"

(M!) - no description, sorry

PARSE>S ( [ccc&lt;char&gt;] char -- addr len ) => [FORTH]

Parse the input stream up to the first occurrence of char, which is parsed away. If executing in compilation mode, append run-time semantics to the current definition that leaves the ANS Forth string representation on the stack. In interpretation mode, leave the ANS Forth string representation for a stored copy, which may be transient in the style of `S`". In either mode, the format of the stored string is implementation dependent. "parse-to-s"

NOTE: The interpreted copy is a nontransient in this implementation, and both copies are mstrings.

S` ( [ccc&lt;`&gt;] -- addr len ) => [FORTH]

An immediate version of parse>s where the delimiter is `. In particular, the stored string in interpret mode is not transient. "s-back-tick"

M,S ( addr len -- addr' len ) => [FORTH]

ALLOT room and store the ANS Forth string into aligned data space as an mstring, leaving data space zero-filled to alignment; and leave the length and new body address. It is assumed that len is unsigned. An error is thrown if len is larger than the system parameter `MAX_DATA_STR`. "m-comma-s"

NOTE: `MAX_DATA_STR` is returned by

        S" /SCOPY" ENVIRONMENT?

NOTE: `M,S` differs from `STRING,` in Wil Baden's Tool Belt in that it stores an aligned, measured string with zero-filled alignment instead of a counted string, and it leaves the ANS Forth string representation of the stored string.

MCOUNT@ ( msa -- count ) => [FORTH]

Fetch the count of the mstring at msa. "m-count-fetch"

MCOUNT! ( count msa -- ) => [FORTH]

Store the count in the measured string count field at msa, without checking that it fits. "m-count-store"

MCOUNT ( msa -- body.addr count ) => [FORTH]

Convert the mstring MSA to its ANS Forth string representation. "m-count"

-MCOUNT ( addr len -- msa ) => [FORTH]

Convert the ANS Forth representation of an mstring to its MSA. "minus-m-count"

($: - no description, sorry

0STRINGS ( -- ) => [FORTH]

Set all string variables holding bound string values in string space to the empty string, and clear string space, including the string buffer, string stack, and string stack frames. "zero-strings"

NOTE: If used for under the hood development, this word must be executed only when string space is in a valid state.

$GARBAGE? ( -- flag ) => [FORTH]

Leave true if there is garbage in the current string space. Not normally used, since garbage collection is transparent. "string-garbage-question"

$GC-OFF ( -- ) => [FORTH]

Disable garbage collection in the current string space. An error will be thrown if garbage collection is attempted. "string-g-c-off"

$GC-ON ( -- ) => [FORTH]

Enable garbage collection in the current string space. This is the default. "string-g-c-on"

$GC-LOCK@ ( -- flag ) => [FORTH]

Fetch the dstring garbage collection "off" state. Intended for saving the off state for later restoration after a usage of `$GC-ON` or `$GC-OFF`. "string-g-c-lock-fetch"

$GC-LOCK! ( flag -- ) => [FORTH]

Set the dstring garbage collection "off" state according to flag. Intended for restoring the off state previously fetched by `$GC-LOCK@`. "string-g-c-lock-fetch"

$UNUSED ( -- u ) => [FORTH]

Leave the number of bytes available for dynamic strings and string stack entries in the string buffer. "string-unused"

COLLECT-$GARBAGE ( -- collected-flag ) => [FORTH]

If string space is not marked as containing garbage, return false. If there is garbage, throw an error when garbage collection is disabled. Otherwise remove the garbage and return true. Garbage collection is "transparent", so the user would not normally use this word. "collect-string-garbage"

MAKE-$SPACE ( size #frames -- addr ) => [FORTH]

Allocate and initialize a string space with size bytes available for the string buffer including the string stack, and with a string frame stack for frame description entries holding up to #frames. The size is rounded up to cell alignment, and the buffer begins and ends with cell alignment. Return addr, the address of the string space. The standard word `FREE` with addr as input can be used to release the space. "make-string-space"

/$BUF ( -- u ) => [FORTH]

Leave the size in address units allocated for the current string buffer. "slash-string-buf"

MAX-#$FRAMES ( -- u ) => [FORTH]

Leave the number of string frames allowed on the string frame stack for the current string space. "max-number-string-frames"

$! ( $var.dfa $: a$ -- ) => [FORTH]

Store the string MSA on the string stack in the variable whose DFA is on the parameter stack. "string-store"

NOTES: The only situation in which `$!` copies the string value is when it is a bound string already stored in another variable. In that case, the new copy is the one that is stored in the variable. In particular, external strings are not copied.

If the string value held by the string variable on entry is a bound string that is also referenced deeper on the string stack, its back link is reset to point to the deepest string stack reference. If it is a bound string not deeper on the string stack and not identical to the input string, its back link is set to zero, making it garbage. If it is an external string, its MSA in the variable is simply written over by that popped from the string stack.

$@ ( $var.pfa -- $: a$ ) => [FORTH]

Leave the MSA of the string held by the string variable. "string-fetch"

(M$:) - no description, sorry

$" ( [ccc&lt;"&gt;] -- $: str ) => [FORTH]

Parse ccc delimited by " (double quote) and store it in data space as an mstring. If interpreting, leave the MSA on the string stack. If compiling, append run-time semantics to the current definition that leaves the MSA on the string stack. A program should not alter the stored string. An error is thrown if the quoted string length is larger than the system parameter `MAX_DATA_STR` (see `SM,`). "string-quote"

NOTE: In contrast to `S"`, the string stored by `$"` when interpreting is not transient.

The implementation is based on PFE code for `S"`.

$` ( [ccc&lt;`&gt;] -- $: str ) => [FORTH]

Parse ccc delimited by ` (back-tick). This is `"$""` with back tick instead of double quote as the delimiter. "string-back-tick"

$VARIABLE ( "name" -- ) => [FORTH]

        "name" execution:	( -- dfa )

Create an ordinary Forth variable and initialize it to the address of a fixed, external, measured representation of the empty string, such as that pushed onto the string stack by `EMPTY\$`. "string-variable""

PARSE>$ ( [ccc&lt;char&gt;] char -- $: ccc$ ) => [FORTH]

Parse the input stream up to the first occurrence of char, which is parsed away, and store the string as an external measured string. If executing in compilation mode, append run-time semantics to the current definition that leaves the MSA on the string stack. In interpretation mode, leave the MSA on the string stack, where the stored copy, unlike `PARSE>S`, is required to be nontransient.

$. ( $: a$ -- ) => [FORTH]

Display the string on the terminal. If the system implementation of TYPE has its output vectored, $. uses the same vector. "string-dot"

$2DROP ( $: a$ b$ -- ) => [FORTH]

Drop the two topmost string stack entries, marking them as garbage if appropriate. "string-two-drop"

$2DUP ( $: a$ b$ -- a$ b$ a$ b$ ) => [FORTH]

Leave copies of the two topmost string stack entries. The string values are not copied. "string-two-dupe"

$DEPTH ( -- n ) => [FORTH]

Leave the number of items on the string stack. "string-depth"

$DROP ( $: a$ -- ) => [FORTH]

Drop the topmost string stack entry, marking it as garbage if it is initially bound to the top of the string stack. "string-drop"

$DUP ( $: a$ -- a$ a$ ) => [FORTH]

Leave a copy of the topmost string stack entry. The string value is not copied. "string-dupe"

$NIP ($: a$ b$ -- b$ ) => [FORTH]

Drop the next to top item from the string stack. "string-nip"

NOTE: Because of essential string space bookkeeping, the system level implementation can be little more efficient than the high-level definition:

        : $NIP  $SWAP $DROP ;

$OVER ( $: a$ b$ -- a$ b$ a$ ) => [FORTH]

Leave a copy of the next most accessible string stack entry on top of the string stack. The string value is not copied. "string-over"

$PICK ( u $: au$ ... a0$ -- au$ ... a0$ au$ ) => [FORTH]

Copy the u-th string stack entry to the top of the string stack. The string value is not copied. Throw an error if the input string stack does not have at least u+1 items. "string-pick"

$SWAP ( $: a$ b$ -- b$ a$ ) => [FORTH]

Exchange the two most accessible strings on the string stack. Throw an error if there are less than two strings on the stack. Neither string value is copied. "string-swap"

$EXCHANGE ( i j -- ) => [FORTH]

($: maxth$ ... minth$ ... -- minth$ ... maxth$ ... ) Exchange the ith and jth strings on the string stack, where the top is the 0th. Throw an error if there are not at least max[i,j] + 1 strings on the stack. Neither string value is copied. "string-exchange"

$S> ( $: a$ -- S: a.s ) => [FORTH]

Drop a$ from the string stack and leave it as a ANS Forth string a.s, without copying. "string-s-from"

WARNING: If a$ is a bound string, it may move or disappear at the next garbage collection, making a.s invalid. This can be avoided by sandwiching sections of code where this could occur between $GC-OFF and $GC-ON.

$,S ( $: a$ -- S: a.s ) => [FORTH]

Drop a$ from the string stack, copy it into data space as a measured string, and leave it as an ANS Forth string a.s. An error is thrown if the string length is larger than the system parameter `MAX_DATA_STR` (see `M,S`). "string-comma-s"

$S@ ( $: a$ -- a$ S: a.s ) => [FORTH]

Leave the string stack unchanged, and leave the string body address and length on the data stack. "string-s-fetch"

WARNING: If a$ is a bound string, it may move at the next garbage collection, making a.s invalid. This can be avoided by sandwiching sections of code where this could occur between $GC-OFF and $GC-ON.

$TUCK ($: a$ b$ -- b$ a$ b$ ) => [FORTH]

Copy the top string stack item just below the second item. The string value is not copied. "string-tuck"

NOTE: Because of essential string space bookkeeping, the system level implementation can be little more efficient than the high-level definition:

        : $TUCK  $SWAP $OVER ;

$TYPE ($: a$ -- ) => [FORTH]

Display the string on the terminal. A deprecated `$.` synonym. "string-type"

>$S-COPY ( a.s -- $: a$ ) => [FORTH]

Copy the external string value whose body address and count are on the parameter stack into the string buffer and push it onto the string stack. Errors are thrown if the count is larger than `MAX_MCOUNT`, if there is not enough room in string space, even after garbage collection, or if there is an unterminated string concatenation. The input external string need not exist as a measured string. "to-string-s-copy"

NOTE: `MAX_MCOUNT` is the largest size the count field of a measured string can hold, e.g., 255, 64K-1, or 4,096M-1. It is returned by:

        S" /DYNAMIC-STRING" ENVIRONMENT?

WARNING: This word should not be used when the input string is a bound string because the copy operation may generate a garbage collection which invalidates its MSA.

>$S ( a.s -- $: a$ ) => [FORTH]

Push the external ANS Forth string a.s onto the string stack, without copying the string value into the string buffer. It is an unchecked error if the Forth string a.s is not stored as an external measured string. "to-string-s"

WARNING: If the string value of a.s is actually in the string buffer and not external, the push operation may generate a garbage collection that invalidates its MSA.

$+ ($: a$ -- ) => [FORTH]

If a$ is the empty string, drop it and do nothing else.

In particular, do not start a new concatenation, which would lock string space against new nonconcatenating copies.

Otherwise append the string body to the end of the string currently being concatenated as the last string in the string buffer, and update its count field. If there is no concatenating string, start one. An error is thrown if the size of the combined string would be larger than `MAX_MCOUNT` or if there is not enough room in string space even after a garbage collection.

If garbage collection occurs, a$ remains valid even when it is in the string buffer.

When there is a concatenating string, concatenation is the only basic string operation that can copy a string into the string buffer. "string-plus"

S+ ( a.s -- ) => [FORTH]

If a.s is the empty string, drop it and do nothing else.

Append the ANS Forth string body to the end of the string currently being concatenated as the last string in the string buffer, and update its count field. If there is no concatenating string, start one. An error is thrown if the size of the combined string would be larger than `MAX_MCOUNT` or if there is not enough room in string space even after a garbage collection.

`S+` is most commonly used on external strings, not assumed to exist as mstrings. In contrast to `$+`, garbage collection could invalidate a.s if it is a dynamic string in the string buffer. `S+` can be used in that situation if garbage collection is turned off with `$GC-OFF`.

When there is a concatenating string, concatenation is the only basic string operation that can copy a string into the string buffer. "s-plus"

PARSE-S+ ( [ccc&lt;char&gt;] char -- ) => [FORTH]

Parse the input stream up to the first occurrence of char, which is parsed away. If executing in compilation mode, append run-time semantics to the current definition that concatenates the characters parsed from the string. Otherwise concatenate the characters. "parse-s-plus"

ENDCAT ( -- $: cat$ | empty$ ) => [FORTH]

If there is no concatenating string, do nothing but leave the empty string. If there is, leave it as a string bound to the top of the string stack, and terminate concatenation, permitting normal copies into the string buffer. "end-cat"

$+" ( [ccc&lt;quote&gt;] -- ) => [FORTH]

This word is immediate. In compilation mode it appends run-time semantics to the current definition that concatenates the quoted string according to the specification for `$+`. In interpretation mode it concatenates the string. An error is thrown if the length of the quoted string is longer than the system parameter `MAX_DATA_STR` (see `M,S`). "string-plus-quote"

$+` ( [ccc&lt;backtick&gt;] -- ) => [FORTH]

The same as `$+"` but with back tick instead of double quote as delimiter. "string-plus-back-tick"

#$ARGS ( -- u ) => [FORTH]

Leave the number of entries in the topmost string frame. Throw an error if the frame stack is empty. "number-string-args"

$ARGS{ ( arg1'$ ... argN'$ "arg1 ... argN &lt;}&gt;" -- ) => [FORTH]

         compilation: ( -- $: arg1$ ... argN$ )

Immediate and compilation-only.

Copy the argument strings across lines to the string buffer, push them onto the string stack with "argN" the most accessible, and make them into the top compile-time string stack frame. Compile the run-time code to make an argument frame out of the N most accessible run-time string stack entries. Inform the system text interpreter that it should compile run-time code for any white-space delimited argument encountered in the text of the definition, that concatenates the corresponding string in the run-time frame. At the semicolon terminating the definition, drop the compile-time argument frame and compile code to drop the run-time argument frame.

The code between `$ARGS{` ... `}` and the terminating semicolon is not allowed to make a net change in the string stack depth, because that would interfere with the automatic dropping of the string argument frame at the semicolon. "string-args-brace"

Syntax for defining a string macro GEORGE:

          : george  ($: a$ b$ c$ -- cat$ )
            $ARGS{ arg1 arg2 arg3 }
            cat" This is arg1:  " arg1 cat" ." ENDCAT $. ;

The blank following the last argument is required. For a macro with no arguments, `$ARGS{ }` does nothing but add useless overhead and should be omitted. Two of the arguments in this example are ignored and could have been left out. Note that `ENDCAT` would not be legal in this word without something like `$.` to remove the concatenated string from the string stack before the terminating semicolon. It is normal to use an `$ARGS{ }` word as a step in a concatenation that is terminated elsewhere.

Sample syntax using the string macro `george`:

          $" bill"  $" sue"  $" marie"  george $.

The resulting display is:

          This is arg1:  bill.

NOTE: Macro argument labels must be distinct from each other and from any local labels that appear in the same definition, and there is no check for that.

NOTE: At the moment the semantics of `$ARGS{` is undefined before `DOES>`.

$FRAME ( u -- ) => [FORTH]

Push the description of a string stack frame starting at the top of the string stack and containing u entries onto the string frame stack. Errors are thrown if the frame stack would overflow or if the depth of the string stack above the top frame, if there is one, is less than u. The value u = 0 is allowed. "string-frame"

NOTE: This implementation pushes u and the string stack pointer onto the frame stack.

$FRAME-DEPTH ( -- u ) => [FORTH]

Leave the number of string frames currently on the string frame stack. "string-frame-depth"

DROP-$FRAME ($: frame*$ i*$ -- i*s ) => [FORTH]

Drop the topmost string frame from the string frame stack, and the corresponding strings, frame*$, from the string stack. An error is thrown if either stack would underflow. The cases where the frame has zero entries on the string stack and/or there are zero or more items on the string stack above the top frame item are handled properly. "drop-string-frame"

FIND-$ARG ( s -- u true | false ) => [FORTH]

Leave true and its index u in the top string frame if the ANS Forth string matches an element of the frame, else leave false. The index of the top frame element is zero. "find-string-arg"

TH-$ARG ( u -- $: arg$ ) => [FORTH]

Leave the u-th string in the topmost string frame, where the index u of the top element is zero. Throw an error if the frame stack is empty or if the top frame contains less than u+1 strings. "th-string-arg"

(DROP-$FRAME) - no description, sorry

$POP ( $: a$ -- s: a$) => [FORTH]

Abort if the string stack would underflow when popped.

Otherwise pop the top of the string stack and push it onto the data stack.

If the string is in the current string space and initially bound to the top of the string stack, mark it as garbage by setting its back link to `NULL` and set the garbage flag.

This word violates the rule that only ANS Forth strings should appear on the data stack, and so is under the hood. "string-pop"

$PUSH-EXT ( a$ -- $: a$ ) => [FORTH]

Pop an external mstring address from the data stack and push it onto the string stack after checking for room, invoking garbage collection if necessary. Not to be used with a dynamic string because a garbage collection can invalidate its address.

This word violates the normal rule that only ANS Forth strings should appear on the data stack, and so is under the hood. "string-push-ext"

$BREAKP@ ( -- $stack.break.addr ) => [FORTH]

"string-break-p-fetch"

$BUFP@ ( -- $buffer.addr ) => [FORTH]

"string-buf-p-fetch"

$FBREAKP@ ( -- frame.stack.break.addr ) => [FORTH]

"string-f-break-p-fetch"

$FSP@ ( -- frame.stack.top.addr ) => [FORTH]

"string-f-s-p-fetch"

$FSP0@ ( -- initial.frame.stack.top.addr ) => [FORTH]

"string-f-s-p-zero-fetch"

$SP@ ( -- string.stack.top.addr ) => [FORTH]

"string-s-p-fetch"

$SP0@ ( -- initial.string.stack.top.addr ) => [FORTH]

"string-s-p-zero-fetch"

/$FRAME-ITEM - no description, sorry

/$FRAME-STACK - no description, sorry

/$SPACE-HEADER ( -- $space.header.size ) => [FORTH]

"slash-string-space-header"

0$SPACE ( $space.addr -- ) => [FORTH]

Clear the string buffer, string stack, and string frame stack in the string space starting at space.addr. Any string variables holding strings in the string buffer are left pointing into limbo. This may be executed with the string space in an invalid state, as long as the `/$BUF` and `MAX-#$FRAMES` fields of its string space structure are intact. "zero-string-space"

NOTE: This word does not zero fill the string buffer.

CAT$P@ ( -- cat$.msa | 0 ) => [FORTH]

"cat-string-fetch"

IN-$BUFFER? ( msa -- flag ) => [FORTH]

Leave true if the mstring is in the string buffer. "in-string-buffer-question"

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