We also allow Kaleidoscope to call into standard library functions (this LLVM +
We also allow Kaleidoscope to call into standard library functions (the LLVM JIT makes this completely trivial). This means that you can use the 'extern' keyword to define a function before you use it (this is also useful for mutually recursive functions). For example:
@@ -90,7 +90,7 @@ eventually add side effects for those who prefer them.In order to make this tutorial maximally understandable and hackable, we choose to implement everything in C++ instead of using lexer and parser generators. LLVM obviously works just fine -with these tools, and choice of these tools doesn't impact overall design.
+with such tools, and making use of them doesn't impact the overall design.A note about this tutorial: we expect you to extend the language and play with it on your own. Take the code and go crazy hacking away at it. It can be @@ -203,7 +203,7 @@ handle them here inline. Numeric values are similar:
This is all pretty straight-forward code for processing input. When reading a numeric value from input, we use the C strtod function to convert it to a numeric value that we store in NumVal. Note that this isn't doing -sufficient error checking: it will incorrect read "1.23.45.67" and handle it as +sufficient error checking: it will incorrectly read "1.23.45.67" and handle it as if you typed in "1.23". Feel free to extend it :). Next we handle comments:
@@ -220,9 +220,9 @@ if you typed in "1.23". Feel free to extend it :). Next we handle comments: -We handle comments by skipping to the end of the line and then returnning the +
We handle comments by skipping to the end of the line and then returning the next comment. Finally, if the input doesn't match one of the above cases, it is -either an operator character like '+', the end of file. These are handled with +either an operator character like '+' or the end of the file. These are handled with this code:
The Error routines are simple helper routines that our parser will use to handle errors. The error recovery in our parser will not be the best and -are not particular user-friendly, but it will be enough for our tutorial. These +is not particular user-friendly, but it will be enough for our tutorial. These routines make it easier to handle errors in routines that have various return types: they always return null.
@@ -284,7 +284,7 @@ return null on an error. calling ParseExpression (we will soon see that ParseExpression can call ParseParenExpr). This is powerful because it allows us to handle recursive grammars, and keeps each production very simple. Note that -parenthesis do not cause construction of AST nodes themselves. While we could +parentheses do not cause construction of AST nodes themselves. While we could do this, the most important role of parens are to guide the parser and provide grouping. Once the parser constructs the AST, parens are not needed. @@ -432,7 +432,7 @@ the expression "a+b+(c+d)*e*f+g". Operator precedence parsing considers this as a stream of primary expressions separated by binary operators. As such, it will first parse the leading primary expression "a", then it will see the pairs [+, b] [+, (c+d)] [*, e] [*, f] and [+, g]. Note that because parentheses -are primary expressions that the binary expression parser doesn't need to worry +are primary expressions, the binary expression parser doesn't need to worry about nested subexpressions like (c+d) at all. @@ -631,7 +631,7 @@ static PrototypeAST *ParsePrototype() {Given this, a function definition is very simple, just a prototype plus -and expression to implement the body:
+an expression to implement the body: