cool overview - lecture 2kjleach.eecs.umich.edu/c18/l2.pdf · cool É classroom objected oriented...

Cool OverviewLecture 2

January 8, 2018

Previously

É Kevin’s Office Hours: Thursdays, 2-4pm, BBB 2717É Lawrence’s Office Hours: Tuesdays/Thursdays,

11am-12:30pm, BBB Learning Center

É Compilers are language processing tools1. Lexing2. Parsing3. Type-checking4. Code generation5. Optimization

Compiler Construction 2/47

COOL

É Classroom Objected Oriented Language

É Easy to lex, parse, and type check

É Also COOL AssemblyÉ We’ll cover it in time for PA5É RISC-based fake-o ISA a la MIPS


Why COOL?


COOL Topics

É Program structureÉ ClassesÉ Attributes/MethodsÉ Types/InheritanceÉ ExpressionsÉ Object creationÉ Built in methodsÉ Dispatch


COOL Program Structure

É Single fileÉ List of classes


COOL Program Structure

É No globals, everything is in a class


COOL Classes

É Everything is inside classesÉ classes defined in any orderÉ classes are top level (no nesting!)


COOL Classes

No nested classes!


COOL Classes

É Each Class is a list of featuresÉ Features are attributes or methods

É All attributes are privateÉ All methods are publicÉ No static methods/attributes


COOL Topics



COOL Attributes and Methods


COOL Topics



COOL Types and Inheritance

É Everything is a class (no virtual, no interfaces)

É “Primitive” boxed typesÉ Int (default 0)É Bool (default false)É String (default empty string, “”)

É Other TypesÉ Main: Boilerplate for code entryÉ IO: inherit this for I/O functions!É Object: Everything inherits Object


COOL Type Hierarchy

Object

Main

IO

Int Bool String

Class A Class B

Subclass C

can’t inherit!


COOL Type Hierarchy

Object

Main

IO

Int Bool String

Class A Class B

Subclass C

can’t inherit!

Inherit from one at a time...


COOL Type Hierarchy

Object

Main

IO

Int Bool String

Class A Class B

Subclass C

can’t inherit!

...or the other


COOL Type Hierarchy

Object

Main

IO

Int Bool String

Class A Class B

Subclass C

can’t inherit!

but no multiple inheritance!


COOL Inheritance


No Inheritance Cycles!


Looking Ahead...

Object

Main

IO

Int Bool String

Class A

Subclass B

Subsubclass C

How might we detect this?


No attribute redefinition


No method signature changes


Method Override


COOL Topics



COOL Expressions

É No statements, only expressionsÉ Expressions have associated types

É Every method contains exactly one expression!


All COOL Expressions

É Constants: 1, true, "Hello"É Arithmetic: 1 + 2, 1 * 3

É Identifiers: xÉ Assignment: x <- exprÉ Comparison: x < 2, 3 <= x

É new: new ClassName

É isvoid: isvoid x


All COOL Expressions (2)

É Conditional:if cond_expr then then_expr else else_expr fi

É Loop:while cond_expr loop body_expr pool

É Blocks:{ expr1 ; expr2 ; ... ; exprn ; }

É Let binding:let x : ClassName <- expr_init in expr_body

É Case:case expr0 of x1 : Class1 => expr1 ; ... ; xn :

Classn => exprn ;


Constant Expression


Arithmetic


Identifier


Assignment


Comparison


new and isvoid


Conditional


Complex Conditional


While Loops


Blocks!


Let


Case


COOL Topics



Object Creation in Cool

É There is a default constructorÉ Basically, run all initializers for attributes


COOL Topics



Built in Methods

É IO : Input/OutputÉ Inherit for access toÉ out_string and in_stringÉ out_int and in_int

É Everything comes from ObjectÉ copy (Shallow copy)É abort (give up execution)É type_name (String with dynamic type)


COOL Topics



Dispatch

É A fancy word for method callsÉ Self, Dynamic, and Static dispatch


Cool List Implementation

É How might we implement a List structure in Cool?


Coming up

É PA1c dueÉ PA1 due 1/17É Lexical Analysis Next

É Brush up on your DFA/NFA/RegExp knowledge


cool overview - lecture 2kjleach.eecs.umich.edu/c18/l2.pdf · cool É classroom objected oriented...

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