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diff --git a/docs/tutorial/OCamlLangImpl6.html b/docs/tutorial/OCamlLangImpl6.html deleted file mode 100644 index 56883d539b..0000000000 --- a/docs/tutorial/OCamlLangImpl6.html +++ /dev/null @@ -1,1574 +0,0 @@ -<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" - "http://www.w3.org/TR/html4/strict.dtd"> - -<html> -<head> - <title>Kaleidoscope: Extending the Language: User-defined Operators</title> - <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> - <meta name="author" content="Chris Lattner"> - <meta name="author" content="Erick Tryzelaar"> - <link rel="stylesheet" href="../_static/llvm.css" type="text/css"> -</head> - -<body> - -<h1>Kaleidoscope: Extending the Language: User-defined Operators</h1> - -<ul> -<li><a href="index.html">Up to Tutorial Index</a></li> -<li>Chapter 6 - <ol> - <li><a href="#intro">Chapter 6 Introduction</a></li> - <li><a href="#idea">User-defined Operators: the Idea</a></li> - <li><a href="#binary">User-defined Binary Operators</a></li> - <li><a href="#unary">User-defined Unary Operators</a></li> - <li><a href="#example">Kicking the Tires</a></li> - <li><a href="#code">Full Code Listing</a></li> - </ol> -</li> -<li><a href="OCamlLangImpl7.html">Chapter 7</a>: Extending the Language: Mutable -Variables / SSA Construction</li> -</ul> - -<div class="doc_author"> - <p> - Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a> - and <a href="mailto:idadesub@users.sourceforge.net">Erick Tryzelaar</a> - </p> -</div> - -<!-- *********************************************************************** --> -<h2><a name="intro">Chapter 6 Introduction</a></h2> -<!-- *********************************************************************** --> - -<div> - -<p>Welcome to Chapter 6 of the "<a href="index.html">Implementing a language -with LLVM</a>" tutorial. At this point in our tutorial, we now have a fully -functional language that is fairly minimal, but also useful. There -is still one big problem with it, however. Our language doesn't have many -useful operators (like division, logical negation, or even any comparisons -besides less-than).</p> - -<p>This chapter of the tutorial takes a wild digression into adding user-defined -operators to the simple and beautiful Kaleidoscope language. This digression now -gives us a simple and ugly language in some ways, but also a powerful one at the -same time. One of the great things about creating your own language is that you -get to decide what is good or bad. In this tutorial we'll assume that it is -okay to use this as a way to show some interesting parsing techniques.</p> - -<p>At the end of this tutorial, we'll run through an example Kaleidoscope -application that <a href="#example">renders the Mandelbrot set</a>. This gives -an example of what you can build with Kaleidoscope and its feature set.</p> - -</div> - -<!-- *********************************************************************** --> -<h2><a name="idea">User-defined Operators: the Idea</a></h2> -<!-- *********************************************************************** --> - -<div> - -<p> -The "operator overloading" that we will add to Kaleidoscope is more general than -languages like C++. In C++, you are only allowed to redefine existing -operators: you can't programatically change the grammar, introduce new -operators, change precedence levels, etc. In this chapter, we will add this -capability to Kaleidoscope, which will let the user round out the set of -operators that are supported.</p> - -<p>The point of going into user-defined operators in a tutorial like this is to -show the power and flexibility of using a hand-written parser. Thus far, the parser -we have been implementing uses recursive descent for most parts of the grammar and -operator precedence parsing for the expressions. See <a -href="OCamlLangImpl2.html">Chapter 2</a> for details. Without using operator -precedence parsing, it would be very difficult to allow the programmer to -introduce new operators into the grammar: the grammar is dynamically extensible -as the JIT runs.</p> - -<p>The two specific features we'll add are programmable unary operators (right -now, Kaleidoscope has no unary operators at all) as well as binary operators. -An example of this is:</p> - -<div class="doc_code"> -<pre> -# Logical unary not. -def unary!(v) - if v then - 0 - else - 1; - -# Define > with the same precedence as <. -def binary> 10 (LHS RHS) - RHS < LHS; - -# Binary "logical or", (note that it does not "short circuit") -def binary| 5 (LHS RHS) - if LHS then - 1 - else if RHS then - 1 - else - 0; - -# Define = with slightly lower precedence than relationals. -def binary= 9 (LHS RHS) - !(LHS < RHS | LHS > RHS); -</pre> -</div> - -<p>Many languages aspire to being able to implement their standard runtime -library in the language itself. In Kaleidoscope, we can implement significant -parts of the language in the library!</p> - -<p>We will break down implementation of these features into two parts: -implementing support for user-defined binary operators and adding unary -operators.</p> - -</div> - -<!-- *********************************************************************** --> -<h2><a name="binary">User-defined Binary Operators</a></h2> -<!-- *********************************************************************** --> - -<div> - -<p>Adding support for user-defined binary operators is pretty simple with our -current framework. We'll first add support for the unary/binary keywords:</p> - -<div class="doc_code"> -<pre> -type token = - ... - <b>(* operators *) - | Binary | Unary</b> - -... - -and lex_ident buffer = parser - ... - | "for" -> [< 'Token.For; stream >] - | "in" -> [< 'Token.In; stream >] - <b>| "binary" -> [< 'Token.Binary; stream >] - | "unary" -> [< 'Token.Unary; stream >]</b> -</pre> -</div> - -<p>This just adds lexer support for the unary and binary keywords, like we -did in <a href="OCamlLangImpl5.html#iflexer">previous chapters</a>. One nice -thing about our current AST, is that we represent binary operators with full -generalisation by using their ASCII code as the opcode. For our extended -operators, we'll use this same representation, so we don't need any new AST or -parser support.</p> - -<p>On the other hand, we have to be able to represent the definitions of these -new operators, in the "def binary| 5" part of the function definition. In our -grammar so far, the "name" for the function definition is parsed as the -"prototype" production and into the <tt>Ast.Prototype</tt> AST node. To -represent our new user-defined operators as prototypes, we have to extend -the <tt>Ast.Prototype</tt> AST node like this:</p> - -<div class="doc_code"> -<pre> -(* proto - This type represents the "prototype" for a function, which captures - * its name, and its argument names (thus implicitly the number of arguments the - * function takes). *) -type proto = - | Prototype of string * string array - <b>| BinOpPrototype of string * string array * int</b> -</pre> -</div> - -<p>Basically, in addition to knowing a name for the prototype, we now keep track -of whether it was an operator, and if it was, what precedence level the operator -is at. The precedence is only used for binary operators (as you'll see below, -it just doesn't apply for unary operators). Now that we have a way to represent -the prototype for a user-defined operator, we need to parse it:</p> - -<div class="doc_code"> -<pre> -(* prototype - * ::= id '(' id* ')' - <b>* ::= binary LETTER number? (id, id) - * ::= unary LETTER number? (id) *)</b> -let parse_prototype = - let rec parse_args accumulator = parser - | [< 'Token.Ident id; e=parse_args (id::accumulator) >] -> e - | [< >] -> accumulator - in - let parse_operator = parser - | [< 'Token.Unary >] -> "unary", 1 - | [< 'Token.Binary >] -> "binary", 2 - in - let parse_binary_precedence = parser - | [< 'Token.Number n >] -> int_of_float n - | [< >] -> 30 - in - parser - | [< 'Token.Ident id; - 'Token.Kwd '(' ?? "expected '(' in prototype"; - args=parse_args []; - 'Token.Kwd ')' ?? "expected ')' in prototype" >] -> - (* success. *) - Ast.Prototype (id, Array.of_list (List.rev args)) - <b>| [< (prefix, kind)=parse_operator; - 'Token.Kwd op ?? "expected an operator"; - (* Read the precedence if present. *) - binary_precedence=parse_binary_precedence; - 'Token.Kwd '(' ?? "expected '(' in prototype"; - args=parse_args []; - 'Token.Kwd ')' ?? "expected ')' in prototype" >] -> - let name = prefix ^ (String.make 1 op) in - let args = Array.of_list (List.rev args) in - - (* Verify right number of arguments for operator. *) - if Array.length args != kind - then raise (Stream.Error "invalid number of operands for operator") - else - if kind == 1 then - Ast.Prototype (name, args) - else - Ast.BinOpPrototype (name, args, binary_precedence)</b> - | [< >] -> - raise (Stream.Error "expected function name in prototype") -</pre> -</div> - -<p>This is all fairly straightforward parsing code, and we have already seen -a lot of similar code in the past. One interesting part about the code above is -the couple lines that set up <tt>name</tt> for binary operators. This builds -names like "binary@" for a newly defined "@" operator. This then takes -advantage of the fact that symbol names in the LLVM symbol table are allowed to -have any character in them, including embedded nul characters.</p> - -<p>The next interesting thing to add, is codegen support for these binary -operators. Given our current structure, this is a simple addition of a default -case for our existing binary operator node:</p> - -<div class="doc_code"> -<pre> -let codegen_expr = function - ... - | Ast.Binary (op, lhs, rhs) -> - let lhs_val = codegen_expr lhs in - let rhs_val = codegen_expr rhs in - begin - match op with - | '+' -> build_add lhs_val rhs_val "addtmp" builder - | '-' -> build_sub lhs_val rhs_val "subtmp" builder - | '*' -> build_mul lhs_val rhs_val "multmp" builder - | '<' -> - (* Convert bool 0/1 to double 0.0 or 1.0 *) - let i = build_fcmp Fcmp.Ult lhs_val rhs_val "cmptmp" builder in - build_uitofp i double_type "booltmp" builder - <b>| _ -> - (* If it wasn't a builtin binary operator, it must be a user defined - * one. Emit a call to it. *) - let callee = "binary" ^ (String.make 1 op) in - let callee = - match lookup_function callee the_module with - | Some callee -> callee - | None -> raise (Error "binary operator not found!") - in - build_call callee [|lhs_val; rhs_val|] "binop" builder</b> - end -</pre> -</div> - -<p>As you can see above, the new code is actually really simple. It just does -a lookup for the appropriate operator in the symbol table and generates a -function call to it. Since user-defined operators are just built as normal -functions (because the "prototype" boils down to a function with the right -name) everything falls into place.</p> - -<p>The final piece of code we are missing, is a bit of top level magic:</p> - -<div class="doc_code"> -<pre> -let codegen_func the_fpm = function - | Ast.Function (proto, body) -> - Hashtbl.clear named_values; - let the_function = codegen_proto proto in - - <b>(* If this is an operator, install it. *) - begin match proto with - | Ast.BinOpPrototype (name, args, prec) -> - let op = name.[String.length name - 1] in - Hashtbl.add Parser.binop_precedence op prec; - | _ -> () - end;</b> - - (* Create a new basic block to start insertion into. *) - let bb = append_block context "entry" the_function in - position_at_end bb builder; - ... -</pre> -</div> - -<p>Basically, before codegening a function, if it is a user-defined operator, we -register it in the precedence table. This allows the binary operator parsing -logic we already have in place to handle it. Since we are working on a -fully-general operator precedence parser, this is all we need to do to "extend -the grammar".</p> - -<p>Now we have useful user-defined binary operators. This builds a lot -on the previous framework we built for other operators. Adding unary operators -is a bit more challenging, because we don't have any framework for it yet - lets -see what it takes.</p> - -</div> - -<!-- *********************************************************************** --> -<h2><a name="unary">User-defined Unary Operators</a></h2> -<!-- *********************************************************************** --> - -<div> - -<p>Since we don't currently support unary operators in the Kaleidoscope -language, we'll need to add everything to support them. Above, we added simple -support for the 'unary' keyword to the lexer. In addition to that, we need an -AST node:</p> - -<div class="doc_code"> -<pre> -type expr = - ... - (* variant for a unary operator. *) - | Unary of char * expr - ... -</pre> -</div> - -<p>This AST node is very simple and obvious by now. It directly mirrors the -binary operator AST node, except that it only has one child. With this, we -need to add the parsing logic. Parsing a unary operator is pretty simple: we'll -add a new function to do it:</p> - -<div class="doc_code"> -<pre> -(* unary - * ::= primary - * ::= '!' unary *) -and parse_unary = parser - (* If this is a unary operator, read it. *) - | [< 'Token.Kwd op when op != '(' && op != ')'; operand=parse_expr >] -> - Ast.Unary (op, operand) - - (* If the current token is not an operator, it must be a primary expr. *) - | [< stream >] -> parse_primary stream -</pre> -</div> - -<p>The grammar we add is pretty straightforward here. If we see a unary -operator when parsing a primary operator, we eat the operator as a prefix and -parse the remaining piece as another unary operator. This allows us to handle -multiple unary operators (e.g. "!!x"). Note that unary operators can't have -ambiguous parses like binary operators can, so there is no need for precedence -information.</p> - -<p>The problem with this function, is that we need to call ParseUnary from -somewhere. To do this, we change previous callers of ParsePrimary to call -<tt>parse_unary</tt> instead:</p> - -<div class="doc_code"> -<pre> -(* binoprhs - * ::= ('+' primary)* *) -and parse_bin_rhs expr_prec lhs stream = - ... - <b>(* Parse the unary expression after the binary operator. *) - let rhs = parse_unary stream in</b> - ... - -... - -(* expression - * ::= primary binoprhs *) -and parse_expr = parser - | [< lhs=<b>parse_unary</b>; stream >] -> parse_bin_rhs 0 lhs stream -</pre> -</div> - -<p>With these two simple changes, we are now able to parse unary operators and build the -AST for them. Next up, we need to add parser support for prototypes, to parse -the unary operator prototype. We extend the binary operator code above -with:</p> - -<div class="doc_code"> -<pre> -(* prototype - * ::= id '(' id* ')' - * ::= binary LETTER number? (id, id) - <b>* ::= unary LETTER number? (id)</b> *) -let parse_prototype = - let rec parse_args accumulator = parser - | [< 'Token.Ident id; e=parse_args (id::accumulator) >] -> e - | [< >] -> accumulator - in - <b>let parse_operator = parser - | [< 'Token.Unary >] -> "unary", 1 - | [< 'Token.Binary >] -> "binary", 2 - in</b> - let parse_binary_precedence = parser - | [< 'Token.Number n >] -> int_of_float n - | [< >] -> 30 - in - parser - | [< 'Token.Ident id; - 'Token.Kwd '(' ?? "expected '(' in prototype"; - args=parse_args []; - 'Token.Kwd ')' ?? "expected ')' in prototype" >] -> - (* success. *) - Ast.Prototype (id, Array.of_list (List.rev args)) - <b>| [< (prefix, kind)=parse_operator; - 'Token.Kwd op ?? "expected an operator"; - (* Read the precedence if present. *) - binary_precedence=parse_binary_precedence; - 'Token.Kwd '(' ?? "expected '(' in prototype"; - args=parse_args []; - 'Token.Kwd ')' ?? "expected ')' in prototype" >] -> - let name = prefix ^ (String.make 1 op) in - let args = Array.of_list (List.rev args) in - - (* Verify right number of arguments for operator. *) - if Array.length args != kind - then raise (Stream.Error "invalid number of operands for operator") - else - if kind == 1 then - Ast.Prototype (name, args) - else - Ast.BinOpPrototype (name, args, binary_precedence)</b> - | [< >] -> - raise (Stream.Error "expected function name in prototype") -</pre> -</div> - -<p>As with binary operators, we name unary operators with a name that includes -the operator character. This assists us at code generation time. Speaking of, -the final piece we need to add is codegen support for unary operators. It looks -like this:</p> - -<div class="doc_code"> -<pre> -let rec codegen_expr = function - ... - | Ast.Unary (op, operand) -> - let operand = codegen_expr operand in - let callee = "unary" ^ (String.make 1 op) in - let callee = - match lookup_function callee the_module with - | Some callee -> callee - | None -> raise (Error "unknown unary operator") - in - build_call callee [|operand|] "unop" builder -</pre> -</div> - -<p>This code is similar to, but simpler than, the code for binary operators. It -is simpler primarily because it doesn't need to handle any predefined operators. -</p> - -</div> - -<!-- *********************************************************************** --> -<h2><a name="example">Kicking the Tires</a></h2> -<!-- *********************************************************************** --> - -<div> - -<p>It is somewhat hard to believe, but with a few simple extensions we've -covered in the last chapters, we have grown a real-ish language. With this, we -can do a lot of interesting things, including I/O, math, and a bunch of other -things. For example, we can now add a nice sequencing operator (printd is -defined to print out the specified value and a newline):</p> - -<div class="doc_code"> -<pre> -ready> <b>extern printd(x);</b> -Read extern: declare double @printd(double) -ready> <b>def binary : 1 (x y) 0; # Low-precedence operator that ignores operands.</b> -.. -ready> <b>printd(123) : printd(456) : printd(789);</b> -123.000000 -456.000000 -789.000000 -Evaluated to 0.000000 -</pre> -</div> - -<p>We can also define a bunch of other "primitive" operations, such as:</p> - -<div class="doc_code"> -<pre> -# Logical unary not. -def unary!(v) - if v then - 0 - else - 1; - -# Unary negate. -def unary-(v) - 0-v; - -# Define > with the same precedence as <. -def binary> 10 (LHS RHS) - RHS < LHS; - -# Binary logical or, which does not short circuit. -def binary| 5 (LHS RHS) - if LHS then - 1 - else if RHS then - 1 - else - 0; - -# Binary logical and, which does not short circuit. -def binary& 6 (LHS RHS) - if !LHS then - 0 - else - !!RHS; - -# Define = with slightly lower precedence than relationals. -def binary = 9 (LHS RHS) - !(LHS < RHS | LHS > RHS); - -</pre> -</div> - - -<p>Given the previous if/then/else support, we can also define interesting -functions for I/O. For example, the following prints out a character whose -"density" reflects the value passed in: the lower the value, the denser the -character:</p> - -<div class="doc_code"> -<pre> -ready> -<b> -extern putchard(char) -def printdensity(d) - if d > 8 then - putchard(32) # ' ' - else if d > 4 then - putchard(46) # '.' - else if d > 2 then - putchard(43) # '+' - else - putchard(42); # '*'</b> -... -ready> <b>printdensity(1): printdensity(2): printdensity(3) : - printdensity(4): printdensity(5): printdensity(9): putchard(10);</b> -*++.. -Evaluated to 0.000000 -</pre> -</div> - -<p>Based on these simple primitive operations, we can start to define more -interesting things. For example, here's a little function that solves for the -number of iterations it takes a function in the complex plane to -converge:</p> - -<div class="doc_code"> -<pre> -# determine whether the specific location diverges. -# Solve for z = z^2 + c in the complex plane. -def mandleconverger(real imag iters creal cimag) - if iters > 255 | (real*real + imag*imag > 4) then - iters - else - mandleconverger(real*real - imag*imag + creal, - 2*real*imag + cimag, - iters+1, creal, cimag); - -# return the number of iterations required for the iteration to escape -def mandleconverge(real imag) - mandleconverger(real, imag, 0, real, imag); -</pre> -</div> - -<p>This "z = z<sup>2</sup> + c" function is a beautiful little creature that is the basis -for computation of the <a -href="http://en.wikipedia.org/wiki/Mandelbrot_set">Mandelbrot Set</a>. Our -<tt>mandelconverge</tt> function returns the number of iterations that it takes -for a complex orbit to escape, saturating to 255. This is not a very useful -function by itself, but if you plot its value over a two-dimensional plane, -you can see the Mandelbrot set. Given that we are limited to using putchard -here, our amazing graphical output is limited, but we can whip together -something using the density plotter above:</p> - -<div class="doc_code"> -<pre> -# compute and plot the mandlebrot set with the specified 2 dimensional range -# info. -def mandelhelp(xmin xmax xstep ymin ymax ystep) - for y = ymin, y < ymax, ystep in ( - (for x = xmin, x < xmax, xstep in - printdensity(mandleconverge(x,y))) - : putchard(10) - ) - -# mandel - This is a convenient helper function for plotting the mandelbrot set -# from the specified position with the specified Magnification. -def mandel(realstart imagstart realmag imagmag) - mandelhelp(realstart, realstart+realmag*78, realmag, - imagstart, imagstart+imagmag*40, imagmag); -</pre> -</div> - -<p>Given this, we can try plotting out the mandlebrot set! Lets try it out:</p> - -<div class="doc_code"> -<pre> -ready> <b>mandel(-2.3, -1.3, 0.05, 0.07);</b> -*******************************+++++++++++************************************* -*************************+++++++++++++++++++++++******************************* -**********************+++++++++++++++++++++++++++++**************************** -*******************+++++++++++++++++++++.. ...++++++++************************* -*****************++++++++++++++++++++++.... ...+++++++++*********************** -***************+++++++++++++++++++++++..... ...+++++++++********************* -**************+++++++++++++++++++++++.... ....+++++++++******************** -*************++++++++++++++++++++++...... .....++++++++******************* -************+++++++++++++++++++++....... .......+++++++****************** -***********+++++++++++++++++++.... ... .+++++++***************** -**********+++++++++++++++++....... .+++++++**************** -*********++++++++++++++........... ...+++++++*************** -********++++++++++++............ ...++++++++************** -********++++++++++... .......... .++++++++************** -*******+++++++++..... .+++++++++************* -*******++++++++...... ..+++++++++************* -*******++++++....... ..+++++++++************* -*******+++++...... ..+++++++++************* -*******.... .... ...+++++++++************* -*******.... . ...+++++++++************* -*******+++++...... ...+++++++++************* -*******++++++....... ..+++++++++************* -*******++++++++...... .+++++++++************* -*******+++++++++..... ..+++++++++************* -********++++++++++... .......... .++++++++************** -********++++++++++++............ ...++++++++************** -*********++++++++++++++.......... ...+++++++*************** -**********++++++++++++++++........ .+++++++**************** -**********++++++++++++++++++++.... ... ..+++++++**************** -***********++++++++++++++++++++++....... .......++++++++***************** -************+++++++++++++++++++++++...... ......++++++++****************** -**************+++++++++++++++++++++++.... ....++++++++******************** -***************+++++++++++++++++++++++..... ...+++++++++********************* -*****************++++++++++++++++++++++.... ...++++++++*********************** -*******************+++++++++++++++++++++......++++++++************************* -*********************++++++++++++++++++++++.++++++++*************************** -*************************+++++++++++++++++++++++******************************* -******************************+++++++++++++************************************ -******************************************************************************* -******************************************************************************* -******************************************************************************* -Evaluated to 0.000000 -ready> <b>mandel(-2, -1, 0.02, 0.04);</b> -**************************+++++++++++++++++++++++++++++++++++++++++++++++++++++ -***********************++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -*********************+++++++++++++++++++++++++++++++++++++++++++++++++++++++++. -*******************+++++++++++++++++++++++++++++++++++++++++++++++++++++++++... -*****************+++++++++++++++++++++++++++++++++++++++++++++++++++++++++..... -***************++++++++++++++++++++++++++++++++++++++++++++++++++++++++........ -**************++++++++++++++++++++++++++++++++++++++++++++++++++++++........... -************+++++++++++++++++++++++++++++++++++++++++++++++++++++.............. -***********++++++++++++++++++++++++++++++++++++++++++++++++++........ . -**********++++++++++++++++++++++++++++++++++++++++++++++............. -********+++++++++++++++++++++++++++++++++++++++++++.................. -*******+++++++++++++++++++++++++++++++++++++++....................... -******+++++++++++++++++++++++++++++++++++........................... -*****++++++++++++++++++++++++++++++++............................ -*****++++++++++++++++++++++++++++............................... -****++++++++++++++++++++++++++...... ......................... -***++++++++++++++++++++++++......... ...... ........... -***++++++++++++++++++++++............ -**+++++++++++++++++++++.............. -**+++++++++++++++++++................ -*++++++++++++++++++................. -*++++++++++++++++............ ... -*++++++++++++++.............. -*+++....++++................ -*.......... ........... -* -*.......... ........... -*+++....++++................ -*++++++++++++++.............. -*++++++++++++++++............ ... -*++++++++++++++++++................. -**+++++++++++++++++++................ -**+++++++++++++++++++++.............. -***++++++++++++++++++++++............ -***++++++++++++++++++++++++......... ...... ........... -****++++++++++++++++++++++++++...... ......................... -*****++++++++++++++++++++++++++++............................... -*****++++++++++++++++++++++++++++++++............................ -******+++++++++++++++++++++++++++++++++++........................... -*******+++++++++++++++++++++++++++++++++++++++....................... -********+++++++++++++++++++++++++++++++++++++++++++.................. -Evaluated to 0.000000 -ready> <b>mandel(-0.9, -1.4, 0.02, 0.03);</b> -******************************************************************************* -******************************************************************************* -******************************************************************************* -**********+++++++++++++++++++++************************************************ -*+++++++++++++++++++++++++++++++++++++++*************************************** -+++++++++++++++++++++++++++++++++++++++++++++********************************** -++++++++++++++++++++++++++++++++++++++++++++++++++***************************** -++++++++++++++++++++++++++++++++++++++++++++++++++++++************************* -+++++++++++++++++++++++++++++++++++++++++++++++++++++++++********************** -+++++++++++++++++++++++++++++++++.........++++++++++++++++++******************* -+++++++++++++++++++++++++++++++.... ......+++++++++++++++++++**************** -+++++++++++++++++++++++++++++....... ........+++++++++++++++++++************** -++++++++++++++++++++++++++++........ ........++++++++++++++++++++************ -+++++++++++++++++++++++++++......... .. ...+++++++++++++++++++++********** -++++++++++++++++++++++++++........... ....++++++++++++++++++++++******** -++++++++++++++++++++++++............. .......++++++++++++++++++++++****** -+++++++++++++++++++++++............. ........+++++++++++++++++++++++**** -++++++++++++++++++++++........... ..........++++++++++++++++++++++*** -++++++++++++++++++++........... .........++++++++++++++++++++++* -++++++++++++++++++............ ...........++++++++++++++++++++ -++++++++++++++++............... .............++++++++++++++++++ -++++++++++++++................. ...............++++++++++++++++ -++++++++++++.................. .................++++++++++++++ -+++++++++.................. .................+++++++++++++ -++++++........ . ......... ..++++++++++++ -++............ ...... ....++++++++++ -.............. ...++++++++++ -.............. ....+++++++++ -.............. .....++++++++ -............. ......++++++++ -........... .......++++++++ -......... ........+++++++ -......... ........+++++++ -......... ....+++++++ -........ ...+++++++ -....... ...+++++++ - ....+++++++ - .....+++++++ - ....+++++++ - ....+++++++ - ....+++++++ -Evaluated to 0.000000 -ready> <b>^D</b> -</pre> -</div> - -<p>At this point, you may be starting to realize that Kaleidoscope is a real -and powerful language. It may not be self-similar :), but it can be used to -plot things that are!</p> - -<p>With this, we conclude the "adding user-defined operators" chapter of the -tutorial. We have successfully augmented our language, adding the ability to -extend the language in the library, and we have shown how this can be used to -build a simple but interesting end-user application in Kaleidoscope. At this -point, Kaleidoscope can build a variety of applications that are functional and -can call functions with side-effects, but it can't actually define and mutate a -variable itself.</p> - -<p>Strikingly, variable mutation is an important feature of some -languages, and it is not at all obvious how to <a href="OCamlLangImpl7.html">add -support for mutable variables</a> without having to add an "SSA construction" -phase to your front-end. In the next chapter, we will describe how you can -add variable mutation without building SSA in your front-end.</p> - -</div> - - -<!-- *********************************************************************** --> -<h2><a name="code">Full Code Listing</a></h2> -<!-- *********************************************************************** --> - -<div> - -<p> -Here is the complete code listing for our running example, enhanced with the -if/then/else and for expressions.. To build this example, use: -</p> - -<div class="doc_code"> -<pre> -# Compile -ocamlbuild toy.byte -# Run -./toy.byte -</pre> -</div> - -<p>Here is the code:</p> - -<dl> -<dt>_tags:</dt> -<dd class="doc_code"> -<pre> -<{lexer,parser}.ml>: use_camlp4, pp(camlp4of) -<*.{byte,native}>: g++, use_llvm, use_llvm_analysis -<*.{byte,native}>: use_llvm_executionengine, use_llvm_target -<*.{byte,native}>: use_llvm_scalar_opts, use_bindings -</pre> -</dd> - -<dt>myocamlbuild.ml:</dt> -<dd class="doc_code"> -<pre> -open Ocamlbuild_plugin;; - -ocaml_lib ~extern:true "llvm";; -ocaml_lib ~extern:true "llvm_analysis";; -ocaml_lib ~extern:true "llvm_executionengine";; -ocaml_lib ~extern:true "llvm_target";; -ocaml_lib ~extern:true "llvm_scalar_opts";; - -flag ["link"; "ocaml"; "g++"] (S[A"-cc"; A"g++"; A"-cclib"; A"-rdynamic"]);; -dep ["link"; "ocaml"; "use_bindings"] ["bindings.o"];; -</pre> -</dd> - -<dt>token.ml:</dt> -<dd class="doc_code"> -<pre> -(*===----------------------------------------------------------------------=== - * Lexer Tokens - *===----------------------------------------------------------------------===*) - -(* The lexer returns these 'Kwd' if it is an unknown character, otherwise one of - * these others for known things. *) -type token = - (* commands *) - | Def | Extern - - (* primary *) - | Ident of string | Number of float - - (* unknown *) - | Kwd of char - - (* control *) - | If | Then | Else - | For | In - - (* operators *) - | Binary | Unary -</pre> -</dd> - -<dt>lexer.ml:</dt> -<dd class="doc_code"> -<pre> -(*===----------------------------------------------------------------------=== - * Lexer - *===----------------------------------------------------------------------===*) - -let rec lex = parser - (* Skip any whitespace. *) - | [< ' (' ' | '\n' | '\r' | '\t'); stream >] -> lex stream - - (* identifier: [a-zA-Z][a-zA-Z0-9] *) - | [< ' ('A' .. 'Z' | 'a' .. 'z' as c); stream >] -> - let buffer = Buffer.create 1 in - Buffer.add_char buffer c; - lex_ident buffer stream - - (* number: [0-9.]+ *) - | [< ' ('0' .. '9' as c); stream >] -> - let buffer = Buffer.create 1 in - Buffer.add_char buffer c; - lex_number buffer stream - - (* Comment until end of line. *) - | [< ' ('#'); stream >] -> - lex_comment stream - - (* Otherwise, just return the character as its ascii value. *) - | [< 'c; stream >] -> - [< 'Token.Kwd c; lex stream >] - - (* end of stream. *) - | [< >] -> [< >] - -and lex_number buffer = parser - | [< ' ('0' .. '9' | '.' as c); stream >] -> - Buffer.add_char buffer c; - lex_number buffer stream - | [< stream=lex >] -> - [< 'Token.Number (float_of_string (Buffer.contents buffer)); stream >] - -and lex_ident buffer = parser - | [< ' ('A' .. 'Z' | 'a' .. 'z' | '0' .. '9' as c); stream >] -> - Buffer.add_char buffer c; - lex_ident buffer stream - | [< stream=lex >] -> - match Buffer.contents buffer with - | "def" -> [< 'Token.Def; stream >] - | "extern" -> [< 'Token.Extern; stream >] - | "if" -> [< 'Token.If; stream >] - | "then" -> [< 'Token.Then; stream >] - | "else" -> [< 'Token.Else; stream >] - | "for" -> [< 'Token.For; stream >] - | "in" -> [< 'Token.In; stream >] - | "binary" -> [< 'Token.Binary; stream >] - | "unary" -> [< 'Token.Unary; stream >] - | id -> [< 'Token.Ident id; stream > |