This is Info file js.info, produced by Makeinfo version 1.68 from the
input file js.texi.

INFO-DIR-SECTION NGS JavaScript Interpreter
START-INFO-DIR-ENTRY
* libjs: (js).			The JavaScript interpreter library.
* js: (js)The js Program.	JavaScript interpreter.
END-INFO-DIR-ENTRY

   This file documents NGS JavaScript interpreter 0.2.5

   Copyright (C) 1998 New Generation Software (NGS) Oy

   Permission is granted to make and distribute verbatim copies of this
manual provided the copyright notice and this permission notice are
preserved on all copies.

   Permission is granted to copy and distribute modified versions of
this manual under the conditions for verbatim copying, provided that
the entire resulting derived work is distributed under the terms of a
permission notice identical to this one.

   Permission is granted to copy and distribute translations of this
manual into another language, under the above conditions for modified
versions, except that this permission notice may be stated in a
translation approved by the Foundation.


File: js.info,  Node: Constants Section,  Next: Symtab Section,  Prev: Code Section,  Up: Byte-Code File Format

Constants Section
-----------------

   The constants section contains the constant values of the byte-code.
The different constant types are stored as follows:

integer
     (UInt8)`3', (Int32)VALUE

string
     (UInt8)`4', (UInt32)LENGTH, LENGTH BYTES OF DATA

float
     (UInt8)`5', (double)VALUE

symbol
     (UInt8)`10', SYMBOL NAME, (UInt8)`0'

NaN
     (UInt8)`13'

regular expression
     (UInt8)`100', (UInt8)FLAGS, (UInt32)LENGTH, LENGTH BYTES OF REGEXP
     SOURCE

     The item FLAGS holds the regular expression flags.  It is a
     combination of the following flags:

    `0x01'
          global match

    `0x02'
          ignore case


File: js.info,  Node: Symtab Section,  Next: Debug Section,  Prev: Constants Section,  Up: Byte-Code File Format

Symtab Section
--------------


File: js.info,  Node: Debug Section,  Prev: Symtab Section,  Up: Byte-Code File Format

Debug Section
-------------


File: js.info,  Node: Byte-Code Operands,  Next: Stack Frame,  Prev: Byte-Code File Format,  Up: Virtual Machine

Byte-Code Operands
==================

   The virtual machine knows the following byte-code operands.  Each
operand is identified by a 8 bit long unsigned integer number.  The
first operand `halt' has code 0, the next operand `done' has code 1,
and so on.  Some operand take arguments that are shown after the
operand name in the following listing.  The meanings of the arguments
are:

`Int8'
     The code of the operand is followed by a 8 bit long integer number
     argument.

`Int16'
     The code of the operand is followed by a 16 bit long integer number
     argument.

`Int32'
     The code of the operand is followed by a 32 bit long integer number
     argument.

`Symbol'
     The code of the operand is followed by a 32 bit long integer number
     argument.  The number is an offset to the constant section and the
     specified constant is a symbol that is the argument of the operand.

   The notation

   BEFORE => AFTER

desribes how the operand modifies the virtual machine stack.  For
example, the notation:

   -- => `undefined'

means that the operand takes no items from the stack and it pushes
value `undefined' to the stack.  The notation:

   ANY ANY => `boolean'

means that the operand takes two items from the stack and it pushes a
boolean result to the stack.

   The virtual machine knows the following byte-code operands.

 - Operand: halt   -- => --
     Halt the virtual machine.  The program execution stops immediately
     and the virtual machine starts execute the following C-code:

          while (1)
            sleep (5);

     This "sleep forever" loop is implemented for debugging purposes.

 - Operand: done   -- => --
     The execution of the byte-code is finished and the control returns
     to the calling C-function.

 - Operand: nop   -- => --
     Do nothing; no operation.

 - Operand: dup   ANY => ANY ANY
     Duplicate the item at the top of the stack.

 - Operand: pop   ANY => --
     Remove one item from the top of the stack.

 - Operand: pop_n `Int8'   ANY ... ANY => --
     Remove INT8 items from the top of the stack.

 - Operand: apop `Int8'   ANY_N ... ANY_0 => ANY_0
     Remove INT8 items from the top of the stack, leaving the topmost
     item on the top of the stack.  This operand is used to remove
     arguments of a function call, leaving the function's return value
     to the top of the stack.

 - Operand: swap   ANY_1 ANY_2 => ANY_2 ANY_1
     Swap the two topmost items in the stack.

 - Operand: roll `Int8'   ANY_N ... ANY_1 ANY_0 => ANY_0 ANY_N ... ANY_1

 - Operand: const `Int32'   -- => CONST
     Push a constant from the constant section to the stack.  The
     constant is specified by the value INT32.

 - Operand: const_null   -- => `null'
     Push value `null' to the stack.

 - Operand: const_true   -- => `true'
     Push value `true' to the stack.

 - Operand: const_false   -- => `false'
     Push value `false' to the stack.

 - Operand: const_undefined   -- => `undefined'
     Push value `undefined' to the stack.

 - Operand: const_i0   -- => `0'
     Push integer number `0' to the stack.

 - Operand: const_i1   -- => `1'
     Push integer number `1' to the stack.

 - Operand: const_i2   -- => `2'
     Push integer number `2' to the stack.

 - Operand: const_i3   -- => `3'
     Push integer number `3' to the stack.

 - Operand: const_i `Int32'   -- => `Int32'
     Push integer number `Int32' to the stack.

 - Operand: load_global `Symbol'   -- => VALUE
     Push the value of the global variable SYMBOL to the stack.  The
     operand will *not* lookup the variable SYMBOL from the with-chain.

 - Operand: store_global `Symbol'   VALUE => --
     Store the topmost item of the stack to the global variable SYMBOL.

 - Operand: load_arg `Int8'   -- => VALUE
     Push the value of the argument INT8 to the stack.

 - Operand: store_arg `Int8'   VALUE => --
     Store the topmost item of the stack to the argument INT8.

 - Operand: load_local `Int16'   -- => VALUE
     Push the value of the local variable INT16 to the stack.

 - Operand: store_local `Int16'   VALUE => --
     Store the topmost item of the stack to the local variable INT16.

 - Operand: load_property `Symbol'   OBJECT => VALUE
     Push the value of the property SYMBOL of object OBJECT to the
     stack.

 - Operand: store_property `Symbol'   OBJECT VALUE => --
     Save the value VALUE to the property SYMBOL of object OBJECT.

 - Operand: load_array   OBJECT INDEX => VALUE
     Push the INDEX:th item of object OBJECT to the stack.

 - Operand: store_array   VALUE OBJECT INDEX => --
     Store the value VALUE to the INDEX:th position of object OBJECT.

 - Operand: nth   ANY INTEGER => ITEM BOOLEAN
     Push the INTEGER:th item of object ANY to the stack.  Push a
     boolean success status that tells whether the object ANY did
     contain INTEGER:th item.

 - Operand: cmp_eq   ANY1 ANY2 => BOOLEAN
     Compare the two objects ANY1, ANY2 for equality and push a boolean
     result code to the stack.

 - Operand: cmp_ne   ANY ANY => BOOLEAN
     Compare the two objects ANY1, ANY2 for inequality and push a
     boolean result code to the stack.

 - Operand: cmp_lt   ANY1 ANY2 => BOOLEAN
     Compare whether object ANY1 is smaller than object ANY2.  Push a
     boolean result code to the stack.

 - Operand: cmp_gt   ANY1 ANY2 => BOOLEAN
     Compare whether object ANY1 is greater than object ANY2.  Push a
     boolean result code to the stack.

 - Operand: cmp_le   ANY1 ANY2 => BOOLEAN
     Compare whether object ANY1 is smaller than, or equal to object
     ANY2.  Push a boolean result code to the stack.

 - Operand: cmp_ge   ANY1 ANY2 => BOOLEAN
     Compare whether object ANY1 is greater than, or equal to object
     ANY2.  Push a boolean result code to the stack.

 - Operand: cmp_seq   ANY1 ANY2 => BOOLEAN
     Compare the two objects ANY1, ANY2 for strict equality and push a
     boolean result code to the stack.

 - Operand: cmp_sne   ANY ANY => BOOLEAN
     Compare the two objects ANY1, ANY2 for strict inequality and push
     a boolean result code to the stack.

 - Operand: sub   ANY1 ANY2 => RESULT
     Substract object ANY2 from object ANY1 and push the result to the
     stack.

 - Operand: add   ANY1 ANY2 => RESULT
     Add object ANY2 to object ANY1 and push the result to the stack.

 - Operand: mul   ANY1 ANY2 => RESULT
     Multiply object ANY1 with object ANY2 and push the result to the
     stack.

 - Operand: div   ANY1 ANY2 => RESULT
     Divide object ANY1 with object ANY2 and push the result to the
     stack.

 - Operand: mod   INTEGER1 INTEGER2 => RESULT
     Count object INTEGER1 modulo object INTEGER2 and push the result
     to the stack.

 - Operand: neg   ANY => RESULT
     Negate object ANY and push the result to the stack.

 - Operand: and   ANY1 ANY2 => RESULT
     Perform a bitwise and operation between objects ANY1 and ANY2 and
     push the result to the stack.

 - Operand: not   ANY1 ANY2 => RESULT
     Perform a bitwise not operation between objects ANY1 and ANY2 and
     push the result to the stack.

 - Operand: or   ANY1 ANY2 => RESULT
     Perform a bitwise or operation between objects ANY1 and ANY2 and
     push the result to the stack.

 - Operand: xor   ANY1 ANY2 => RESULT
     Perform a bitwise xor operation between objects ANY1 and ANY2 and
     push the result to the stack.

 - Operand: shift_left   INTEGER1 INTEGER2 => INTEGER
     Shift integer number INTEGER1 left INTEGER2 bits.  Push the result
     value to the stack.

 - Operand: shift_right   INTEGER1 INTEGER2 => INTEGER
     Shift integer number INTEGER1 right INTEGER2 bits.  Push the
     result value to the stack.

 - Operand: shift_rright   INTEGER1 INTEGER2 => INTEGER

 - Operand: iffalse `Int32'   ANY => --
     If the topmost item in the stack has boolean value `false', adjust
     the program counter with relative offset INT32.

 - Operand: iftrue `Int32'   ANY => --
     If the topmost item in the stack has boolean value `true', adjust
     the program counter with relative offset INT32.

 - Operand: call_method `Symbol'   OBJECT => RESULT
     Call method SYMBOL in the object OBJECT.  Push the result of the
     method call to the stack.

 - Operand: jmp `Int32'   -- => --
     Adjust program counter with relative offset INT32, e.g. jump to
     relative position PC + INT32.

 - Operand: jsr   FUNCTION => RESULT
     Jump to subroutine FUNCTION and push the result of the subroutine
     call to the stack.  The operand will *not* process the with-chain.

 - Operand: return   RESULT => RESULT
     Return from a subroutine with value RESULT.

 - Operand: typeof   ANY => STRING
     Push the type name of object ANY to the stack.

 - Operand: new   OBJECT => RESULT OBJECT
     Create an instance of object OBJECT and call its constructor
     function.  Push the result from the constructor and the new
     instance to the stack.  The return value of the constructor is
     discarded.

 - Operand: delete_property `Symbol'   OBJECT => UNDEFINED
     Delete property SYMBOL from object OBJECT.  Push value `undefined'
     to the stack.

 - Operand: delete_array   OBJECT INDEX => UNDEFINED
     Delete the INDEX:th property of object OBJECT.  Push value
     `undefined' to the stack.

 - Operand: locals `Int16'   -- => UNDEFINED ... UNDEFINED
     Allocate INT16 local variables from the stack frame.  The operand
     `locals' must be called in the beginning of the function code.  The
     operand will push INT16 `undefined' values to the stack.  The
     values will be the place-holders for the local variables.

 - Operand: min_args `Int8'   INTEGER => --
     If the number of the arguments for the function INTEGER is smaller
     than `Int8', expand the stack frame so that the function gets
     `Int8' arguments.  The created arguments will have value
     `undefined'.

 - Operand: load_nth_arg   INTEGER => ARGUMENT
     Push the INTEGER'th argument of function to the top of the stack.
     The index INTEGER must be an integer number.

 - Operand: with_push   OBJECT => --
     Push object OBJECT to the function's with-lookup chain.

 - Operand: with_pop `Int8'   -- => --
     Pop INT8 objects from the function's with-lookup chain.

 - Operand: try_push `Int32'   -- => --
     Push a try-frame with a catch block offset INT32 to the virtual
     machine's try-chain.

 - Operand: try_pop `Int8'   -- => --
     Pop INT8 frames from the virtual machine's try-chain.

 - Operand: throw   ANY => --
     Throw an exception with value ANY.

 - Operand: iffalse_b `Int32'   BOOLEAN => --
     If the topmost item in the stack is `false', adjust the program
     counter with relative offset INT32.  The operand assumes that the
     topmost item is a boolean value.

 - Operand: iftrue_b `Int32'   BOOLEAN => --
     If the topmost item in the stack is `true', adjust the program
     counter with relative offset INT32.  The operand assumes that the
     topmost item is a boolean value.

 - Operand: add_1_i   INTEGER => INTEGER
     Add integer number one to the top most item in the stack.  The
     operand assumes that the topmost item is an integer number.

 - Operand: add_2_i   INTEGER => INTEGER
     Add integer number two to the top most item in the stack.  The
     operand assumes that the topmost item is an integer number.

 - Operand: load_global_w `Symbol'   -- => VALUE
     Push the value of the global variable SYMBOL to the stack.  The
     operand will lookup the property SYMBOL from the currently active
     with-chain.

 - Operand: jsr_w `Symbol'   FUNCTION => RESULT
     Jump to subroutine FUNCTION and push the result of the subroutine
     call to the stack.  The operand will lookup the method SYMBOL from
     the currently active with-chain.  If the method is not found, the
     argument FUNCTION is used.


File: js.info,  Node: Stack Frame,  Prev: Byte-Code Operands,  Up: Virtual Machine

Stack Frame
===========

     JS_SP0  sp =>
     JS_SP1          local_var_N
     JS_SP2          ...
     JS_SP(N)        local_var_1
     JS_LOCAL(0)     local_var_0
                     return_addr
     JS_WITHPTR      with_ptr
     JS_ARGS_FIXP    args_fix
             fp =>   old_fp
     JS_ARG(0)       this
     JS_ARG(1)       arg_count
     JS_ARG(2)       argument_1
                     argument_2
                     ...
     JS_ARG(N)       argument_N
                     local_var_N
                     ...
                     local_var_0
                     args_fix
                     return_addr
                     with_ptr
                     old_fp
                     this
                     ...


File: js.info,  Node: JavaScript Compiler,  Next: GNU Library General Public License,  Prev: Virtual Machine,  Up: Top

JavaScript Compiler
*******************

   The JavaScript compiler is implemented in the JavaScript language.
Because the JavaScript language does not have namespaces, the compiler
has been coded to a fixed part of the global namespace.  All global
symbols the compiler uses, start with the prefix ``JSC$''.  This prefix
is reserved for the interpreter and users must not define any symbols
or functions starting with that prefix.

   The compiler compiles JavaScript source code to byte-code and it
returns a fixed byte-code file as the result.  This result file (or
data block) can be passed to the virtual machine for execution.

   The compiler has three stages.  The first stage parse the input
stream and create a syntax tree for the input.  The second stage
transforms the syntax tree to a list of assembler operations.  The
third stage converts the symbolic assembler instructions to byte-code
operands.

   Depending on the compilation options, the compiler performs different
optimizations during the compilation.  The basic optimizations include
constant folding, peephole optimization, and optimization of jumps to
jump instructions.  During the batch-compilation (when compiling a
JavaScript source file `.js' to byte-code file `.jsc') the compiler
performns heavier optimizations to minimize the size of the generated
byte-code file, and to speed up some operations.

* Menu:

* Public Entry Points::


File: js.info,  Node: Public Entry Points,  Prev: JavaScript Compiler,  Up: JavaScript Compiler

Public Entry Points
===================

 - Function: JSC$compile_file (NAME, FLAGS, ASM_FILE, BC_FILE)
     Compile JavaScript source file NAME according to FLAGS.  If
     argument ASM_FILE is not `null', symbolic assembler output is
     saved to that file.  If argument BC_FILE is not `null', the
     byte-code output is saved to that file.

     The function returns a string that holds the byte-code output for
     the source file.

 - Function: JSC$compile_string (STRING, FLAGS, ASM_FILE, BC_FILE)
     Compile JavaScript source code STRING according to FLAGS.  If
     argument ASM_FILE is not `null', symbolic assembler output is
     saved to that file.  If argument BC_FILE is not `null', the
     byte-code output is saved to that file.

     The function returns a string that holds the byte-code output for
     the source code.

   In both functions, the argument FLAGS specify the verbosity,
warning, and optimization levels of the compilation.  The following
values can be given to flags:

`JSC$FLAG_VERBOSE'
     turns on diagnostic messages

`JSC$FLAG_ANNOTATE_ASSEMBLER'
     add original JavaScript source lines to the generated assembler
     listing

`JSC$FLAG_GENERATE_DEBUG_INFO'
     generate debugging information to the byte-code file

`JSC$FLAG_GENERATE_EXECUTABLE_BC_FILES'
     add execute permissions to the generated byte-code files

`JSC$FLAG_OPTIMIZE_PEEPHOLE'
     perform peephole optimization

`JSC$FLAG_OPTIMIZE_JUMPS'
     perform optimization for jumps to jump instructions

`JSC$FLAG_OPTIMIZE_BC_SIZE'
     optimize the size of the genated byte-code file

`JSC$FLAG_OPTIMIZE_HEAVY'
     perform optimizations which require liveness analyzing of the
     variables

`JSC$FLAG_OPTIMIZE_MASK'
     mask to turn on all optimizations

`JSC$FLAG_WARN_UNUSED_ARGUMENT'
     warn if an argument of a function is unused in the function body

`JSC$FLAG_WARN_UNUSED_VARIABLE'
     warn in a variable is defined but it is not used in the function
     body

`JSC$FLAG_WARN_SHADOW'
     warn if a variable declaration shadows a parameter of a function

`JSC$FLAG_WARN_WITH_CLOBBER'
     warn if a symbol with-lookup is clobbered because the symbol is
     defined to be a local variable or a function argument

`JSC$FLAG_WARN_MISSING_SEMICOLON'
     warn if a semicolon is missing from the input.  The missing
     semicolons are inserted during the parsing by the automatic
     semicolon inserting.  However, since the missing semicolons show
     bad programming style, this option will warn about them.

`JSC$FLAG_WARN_STRICT_ECMA'
     warn about things that are supported by this implementation, but
     are not allowed by the ECMAScript standard

`JSC$FLAG_WARN_DEPRECATED'
     warn if deprecated features has been used in the source code

`JSC$FLAG_WARN_MASK'
     mask to turn on all warnings

   The compiler entry points can be called from JavaScript and C
programs.  For example, they are used extensively to implement the
JavaScript API, described in the `js.h' file.  The following example
shows how a C-string, containing JavaScript code, can be compiled and
executed.  Similar function can be found from the JavaScript API
implementing the `js_eval()' function.

     int
     eval_code (JSInterpPtr interp, char *code);
     {
       JSNode argv[5];
       int i = 0;
       int result;
       ByteCode *bc;
     
       /* Compile the code. */
     
       /* Argument count. */
       argv[i].type = JS_INTEGER;
       argv[i].u.vinteger = 4;
       i++;
     
       /* Source for the compiler. */
       js_make_static_string (interp->vm, &argv[i], code, strlen (code));
       i++;
     
       /* Flags. */
       argv[i].type = JS_INTEGER;
       argv[i].u.vinteger = JSC_FLAG_VERBOSE;
       argv[i].u.vinteger |= JSC_FLAG_OPTIMIZE_MASK;
       argv[i].u.vinteger |= JSC_FLAG_WARN_MASK;
       i++;
     
       /* Assembler file. */
       argv[i].type = JS_NULL;
       i++;
     
       /* Byte-code file. */
       argv[i].type = JS_NULL;
       i++;
     
       /* Call the compiler entry point. */
       result = js_vm_apply (interp->vm, "JSC$compile_string", i, argv);
       if (result == 0)
         return 0;
     
       bc = js_bc_read_data (interp->vm->exec_result.u.vstring->data,
                             interp->vm->exec_result.u.vstring->len);
     
       /* And finally, execute it. */
       result = js_vm_execute (interp->vm, bc);
     
       /* Free the byte-code. */
       js_bc_free (bc);
     
       return result;
     }

   The following example shows how the compiler entry point can be
called from JavaScript code.  The example code compiles a JavaScript
source code file `input.js' into byte-code and stores the result to file
`ouput.jsc'.

     try
       {
         JSC$compile_file ("input.js",
           		JSC$FLAG_OPTIMIZE_MASK | JSC$FLAG_WARN_MASK,
           		null, "output.jsc");
       }
     catch (e)
       {
         System.stdout.writeln ("compilation failed: " + e);
       }


File: js.info,  Node: GNU Library General Public License,  Next: Index,  Prev: JavaScript Compiler,  Up: Top

GNU Library General Public License
**********************************

GNU LIBRARY GENERAL PUBLIC LICENSE
**********************************

                         Version 2, June 1991

     Copyright (C) 1991 Free Software Foundation, Inc.
     59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
     Everyone is permitted to copy and distribute verbatim copies
     of this license document, but changing it is not allowed.
     
     [This is the first released version of the library GPL.  It is
      numbered 2 because it goes with version 2 of the ordinary GPL.]

Preamble
========

   The licenses for most software are designed to take away your
freedom to share and change it.  By contrast, the GNU General Public
Licenses are intended to guarantee your freedom to share and change
free software--to make sure the software is free for all its users.

   This license, the Library General Public License, applies to some
specially designated Free Software Foundation software, and to any
other libraries whose authors decide to use it.  You can use it for
your libraries, too.

   When we speak of free software, we are referring to freedom, not
price.  Our General Public Licenses are designed to make sure that you
have the freedom to distribute copies of free software (and charge for
this service if you wish), that you receive source code or can get it
if you want it, that you can change the software or use pieces of it in
new free programs; and that you know you can do these things.

   To protect your rights, we need to make restrictions that forbid
anyone to deny you these rights or to ask you to surrender the rights.
These restrictions translate to certain responsibilities for you if you
distribute copies of the library, or if you modify it.

   For example, if you distribute copies of the library, whether gratis
or for a fee, you must give the recipients all the rights that we gave
you.  You must make sure that they, too, receive or can get the source
code.  If you link a program with the library, you must provide
complete object files to the recipients so that they can relink them
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it.  And you must show them these terms so they know their rights.

   Our method of protecting your rights has two steps: (1) copyright
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permission to copy, distribute and/or modify the library.

   Also, for each distributor's protection, we want to make certain
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   Finally, any free program is threatened constantly by software
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   Note that it is possible for a library to be covered by the ordinary
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How to Apply These Terms to Your New Libraries
==============================================

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   That's all there is to it!

