Introduction to Language Processing Technology

1
Introduction to Language Processing Technology

• Natawut Nupairoj, Ph.D.
• Department of Computer Engineering
• Chulalongkorn University

2
Outline

• Level of Programming Languages.
• Language Processors.
• Specification of Programming Languages.

3
Level of Programming Languages

• swap(int v, int k)
• int temp
• temp vk
• vk vk1
• vk1 temp
• swap
• muli 2, 5, 4
• add 2, 4, 2
• lw 15, 0(2)
• ...

• High level C / Java / Pascal
• Low level Assembly / Bytecode
• Machine Language

• 000010001101101100110000
• 000010001101101100110000
• 000010001101101100110000
• 000010001101101100110000
• ...

C Compiler
Assembler
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High-Level Language Characteristics

• Expressions
• a b (c d)/2
• Data types
• Integer, character, boolean.
• Record, array.
• Control structures
• Selective.
• Iterative.

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High-Level Language Characteristics

• Declarations
• Identifier can be constant, variable, procedure,
  function, and type.
• Abstraction
• Object-oriented concept.
• Concern only what, not how.
• Encapsulation
• Object-oriented concept.
• Information hiding.

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Language Processors

• Program that manipulates programs express in some
  programming languages.
• Example
• Editor.
• Translator / Compiler.
• Interpreter.

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Translator

• Translate a source program into an equivalent
  object program.

C C FORTRAN Java VB
Assembly C Bytecode p-code
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Tombstone Diagrams

• Ordinary program

Program P
Written with Language L
9
Tombstone Diagrams

• Machine

SPARC
x86
Machine M
M
x86
SPARC
10
Tombstone Diagrams

• Translator

S is translated to T
Translator is written with Language L
11
Tombstone Diagrams

• Compilation

x86
12
Tombstone Diagrams

• Cross Compilation

SPARC
13
Tombstone Diagrams

• Two-stage compilation

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Tombstone Diagrams

• Compiling a compiler

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Tombstone Diagrams

• Interpreter

Basic x86
Interpret source S
S L
Basic x86
SQL SPARC
x86
Written in language L
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Tombstone Diagrams

• Abstract machine hardware emulator
• interpreter for low-level language.

370 x86

x86
17
Tombstone Diagrams

• Java
• Portable environment write-once-run-anywhere.
• Interpretive compiler.

JVM Bytecode
JVM M
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Tombstone Diagrams
19
Tombstone Diagrams

• Bootstrapping
• Compiler L that is written on L language.
• Full bootstrap
• Start from nothing.
• Half bootstrap
• Start from other machine.

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Tombstone Diagrams

• Full Bootstrap

NNP
NNP
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Tombstone Diagrams
NNP
22
Tombstone Diagrams
NNP
NNP
NNP
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Tombstone Diagrams

• Half Bootstrap

x86
x86
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Specification of Programming Language

• Specification
• Syntax
• Define symbol and structure of the language.
• Grammar.
• Contextual constraints
• Constraints beyond grammar.
• Rules of the language scope rules, type rules,
  etc.
• Semantics
• Meaning of program its behaviors when run.
• How to translate a sentence S of the language L
  to a machine code on M

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Syntax

• Context-free grammar
• Terminals.
• Non-terminals / Variables.
• Start symbol.
• Production rules.
• Usually being expressed with BNF notation.

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BNF Notation

• Backus-Naur Form.
• Given production rule
• N a
• N b
• Can be written as
• N a b

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Example Mini-Triangle Program

• ! This is a comment. It continues to the
  end-of-line.
• let
• const m 7
• var n Integer
• in
• begin
• n 2 m m
• putint(n)
• end

Terminals begin const do else end if in let then v
ar while ( ) - / lt gt \
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Mini-Triangle Syntax

• Program Command
• Command single-Command
• Command single-Command
• single-Command V-name Expression
• Identifier ( Expression )
• if Expression then single-Command
• else single-Command
• while Expression do single-Command
• let Declaration in single-Command
• begin Command end

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Mini-Triangle Syntax

• Expression primary-Expression
• Expression Operator primary-Expression
• primary-Expression Integer-Literal
• V-name
• Operator primary-Expression
• ( Expression )
• V-name Identifier
• Declaration single-Declaration
• Declaration single-Declaration
• single-Declaration const Identifier
  Expression
• var Identifier Type-denoter

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Mini-Triangle Syntax

• Type-denoter Identifier
• Operator - / lt gt \
• Identifier Letter Identifier Letter
• Identifier Digit
• Integer-Literal Digit Integer-Literal Digit
• Comment ! Graphic eol
• Letter a b z
• Digit 0 1 2 9

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Syntax Tree

• Ordered tree with
• Internal nodes non-terminals.
• Leaf nodes terminals.
• N-tree of G is a syntax tree with N as the root.

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Mini-Triangle Syntax Tree

• Expression primary-Expression
• Expression Operator
• primary-Expression
• primary-Expression Integer-Literal
• V-name
• Operator
• primary-Expression
• ( Expression )
• V-name Identifier