Apertium-recursive/Bytecode

File Structure

Recursive transfer bytecode files are written using Lttoolbox/compression.h. The structure of the file is as follows:

Length of the longest input-time pattern (including blanks)
Number of input-time rules
[
  for each input-time rule:
  the length the pattern
  the the rule
]
Number of output-time rules
Bytecode of each rule
Alphabet for the pattern transducer
Pattern transducer
The mapping from final states to rules
Attribute patterns
Global variables
Lists

Datatypes

The datatypes available to bytecode instructions are string, integer, boolean, and Chunk, where Chunk objects represent lexical units, chunks, and blanks.

Bytecode Operations

[int] after the name indicates that this instruction is two characters long and the second is to be interpreted as an integer.

Name	Action	Stack before	Stack after
drop	pop the top of the stack	[1] X [2] ...	[1] ...
dup	push a copy of the top element	[1] X [2] ...	[1] X [2] X [3] ...
over	push a copy of the second element	[1] X [2] Y [3] ...	[1] Y [2] X [3] Y [4] ...
swap	exchange the first and second elements	[1] X [2] Y [3] ...	[1] Y [2] X [3] ...
string [int]	pushes the next [int] characters onto the stack as a literal string	[1] ...	[1] string [2] ...
int [int]	pushes [int] onto the stack	[1] ...	[1] int [2] ...
pushfalse	pushes false onto the stack	[1] ...	[1] false [2] ...
pushtrue	pushes true onto the stack	[1] ...	[1] true [2] ...
jump [int]	increments the instruction pointer by [int]	[1] ...	[1] ...
jumpontrue [int]	pops a bool off the stack and increments the instruction pointer by [int] if it is true	[1] bool [2] ...	[1] ...
jumponfalse [int]	pops a bool off the stack and increments the instruction pointer by [int] if it is false	[1] bool [2] ...	[1] ...
and	pops 2 bools of the stack and pushes whether both of them are true	[1] bool [2] bool [3] ...	[1] bool [2] ...
or	pops 2 bools of the stack and pushes whether either of them is true	[1] bool [2] bool [3] ...	[1] bool [2] ...
not	logically negates top of stack	[1] bool [2] ...	[1] bool [2] ...
equal	push whether the first two strings popped are the same	[1] string [2] string [3] ...	[1] bool [2] ...
isprefix	push whether the first string popped occurs at the beginning of the second	[1] string (part) [2] string (whole) [3] ...	[1] bool [2] ...
issuffix	push whether the first string popped occurs at the end of the second	[1] string (part) [2] string (whole) [3] ...	[1] bool [2] ...
issubstring	pushes whether the first string popped appears anywhere in the second	[1] string (part) [2] string (whole) [3] ...	[1] bool [2] ...
equalcl	equal, but ignores case	[1] string [2] string [3] ...	[1] bool [2] ...
isprefixcl	isprefix, but ignores case	[1] string (part) [2] string (whole) [3] ...	[1] bool [2] ...
issuffixcl	issuffix, but ignores case	[1] string (part) [2] string (whole) [3] ...	[1] bool [2] ...
issubstringcl	issubstring, but ignores case	[1] string (part) [2] string (whole) [3] ...	[1] bool [2] ...
hasprefix	push whether the second string popped begins with any member of the list named by the first string popped	[1] string (list) [2] string [3] ...	[1] bool [2] ...
hassuffix	push whether the second string popped ends with any member of the list named by the first string popped	[1] string (list) [2] string [3] ...	[1] bool [2] ...
in	push whether the second string popped is a member of the list named by the first	[1] string (list) [2] string [3] ...	[1] bool [2] ...
hasprefixcl	hasprefix, but ignores case	[1] string (list) [2] string [3] ...	[1] bool [2] ...
hassuffixcl	hassuffix, but ignores case	[1] string (list) [2] string [3] ...	[1] bool [2] ...
incl	in, but ignores case	[1] string (list) [2] string [3] ...	[1] bool [2] ...
getcase	pushes "aa", "Aa", or "AA", depending on the case of the first string popped	[1] string (text) [2] ...	[1] string (case) [2] ...
setcase	pops two strings, copies the case of the first to the second and pushes the result	[1] string (case) [2] string (text) [3] ...	[1] string (text) [2] ...
fetchvar	pops a string and pushes the value of the variable with that name	[1] string (name) [2] ...	[1] string (value) [2] ...
setvar	pops a two strings and sets the second as the value of the variable named by the first	[1] string (name) [2] string (value) [3] ...	[1] ...
sourceclip	pops an int and a string, pushes the value of the source-side clip identified by them	[1] int [2] string (part) [3] ...	[1] string (clip) [2] ...
targetclip	pops an int and a string, pushes the value of the target-side clip identified by them	[1] int [2] string (part) [3] ...	[1] string (clip) [2] ...
referenceclip	pops an int and a string, pushes the value of the reference-side clip identified by them	[1] int [2] string (part) [3] ...	[1] string (clip) [2] ...
setclip	pops an int and two strings, sets the second string as the value of the target-side clip identified by the int and the first string. If the integer is 0, the chunk on top of the stack is used.	[1] int [2] string (part) [3] string (value) [4] (chunk) [5] ...	[1] (chunk) [2] ...
chunk	creates an empty chunk and pushes it	[1] ...	[1] chunk [2] ...
appendchild	pops a chunk and appends it as a child to the chunk underneath it (which remains on the stack)	[1] chunk (child) [2] chunk (parent) [3] ...	[1] chunk (parent) [2] ...
appendsurface	pops a string and appends it to the target-side surface chunk underneath it (which remains on the stack)	[1] string [2] chunk [3] ...	[1] chunk [2] ...
appendallchildren	pops a chunk and appends all of its children as children to the chunk underneath it (which remains on the stack)	[1] chunk (source) [2] chunk (destination) [3] ...	[1] chunk (destination) [2] ...
output	pops a chunk and appends it to the output queue	[1] chunk [2] ...	[1] ...
appendallinput	append the entire input queue as children of the chunk on top of the stack	[1] chunk [2] ...	[1] chunk [2] ...
blank	pops an int and pushes the corresponding blank (or a single space if the int is 0)	[1] int [2] ...	[1] chunk (blank) [2] ...
outputall	moves everything in the input queue to the output queue and ends the rule execution (creates a no-op rule)	[1] ...	[1] ...
concat	pops two strings, concatenates them, and pushes the result	[1] string X [2] string Y [3] ...	[1] string YX [2] ...
rejectrule	abort evaluation of current rule and attempt to match a different one	[1] ...	[1] ...
distag	removes initial < and final > from the string on top of the stack (this makes compiling comparisons easier)	[1] string (tag) [2] ...	[1] string (text) [2] ...
getrule	pop an int and push the index of the output rule associated with the chunk in that position.	[1] int (position) [2] ...	[1] int (rule) [2] ...
setrule	pop an int and set it as the index of the output rule of the chunk on top of the stack	[1] int (rule) [2] chunk [3] ...	[1] chunk [2] ...
lucount	push a string corresponding to the number of chunks in the input to the rule	[1] ...	[1] string (number) [2] ...