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28 Cards in this Set
- Front
- Back
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Key characteristics that distinguish programming languages from other languages
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1.) govern some process on the computer
2.) unambigous 3.) formally defined 4.) static |
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What are the two ways of having n machines and i languages and being able to run the languages on the machines
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1.) L2...LM all translate to L1, L1 -> each machine is (L + M - 1)
2.) Each language is converted to each machine (L*M) |
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What is used as a widespread intermediate language
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C
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What does an interpreter require that a translator doesnt
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A program AND data
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Assembler
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translator
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simulator
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interpreter
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JVM
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Java virtual machine interpreter written for machine hardware
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JIT
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Just in time - only happens in interpreters, during execution, java byte code is converted to machine code and then run in hardware rather than through software
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When using JIT the compiler must
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1.) keep track of where it called from
2.) keep track of what has been compiled to machine code 3.) keep track of current state |
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Criteria for evaluating programming languages
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Readability
Writability Reliability Overall cost |
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Value of a programming langauge is dependent on..
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problem-solving domain
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What is programming language designs based on
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Machine architecture and software design methodologies
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Syntax
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What are legal programs in some programming language
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What is syntax described with
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CFG, BNF,EBNF
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Semantics
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What do the instructions of a PL do in execution
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What is used to describe semantics
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english
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methodology
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what are you supposed to use the features of a langue for
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Runtime versus compile-time
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Pure translation or interpretation is easy to identify
Jit is harder to determine |
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BNF
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Backus naur Form used to describe syntax
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Nonterminals
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<>
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terminals
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0,1,2, etc
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EBNF [] {} * +
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optional, repetition (0 or more), repetition (0 or more), repetition (1 or more)
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BNF vs EBNF
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BNF is based on context free grammar and can be parsed with recursive descent while EBNF has additional symbols and is parsed with iteration not recursion
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Ambigious grammar
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two ways to derive a parse tree for the same string
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Concrete vs abstract parse tree
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Abstract eliminates unnecessary terminals and leaves the nonterminals
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Writability
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How easy it is to create programs for a chosen problem domain
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reliability
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performs to its specifications under all conditions: type checking, exception handling
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cost
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training, writing, compiling, executing programs
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