Welcome to CS251 Interpreter and Translators Theory of Programming - - PowerPoint PPT Presentation

Introduction Interpretation and Translation Interpretation versus Translation Boot Strapping

Welcome to CS251 Interpreter and Translators

Theory of Programming Languages Computer Science Department Wellesley College

Introduction Interpretation and Translation Interpretation versus Translation Boot Strapping

Table of contents

Introduction Interpretation and Translation Interpretation versus Translation Boot Strapping

Introduction Interpretation and Translation Interpretation versus Translation Boot Strapping

Analyzing programming languages

Introduction Interpretation and Translation Interpretation versus Translation Boot Strapping

You control the horizontal

Life stages:

• Applications user;
• programmer;
• language designer.

Introduction Interpretation and Translation Interpretation versus Translation Boot Strapping

Under the hood

There are two fundamental approaches to programming language implementation:

• 1. Interpreting one language (the source language) on top of

another (the implementation language);

• 2. translating a program in one language (the source language)

into another programming language (the target language) via a translation program written in an implementation language.

Introduction Interpretation and Translation Interpretation versus Translation Boot Strapping

Interpreters and compilers

There are two basic reasoning rules involving interpreters and translators (a.k.a. compilers):

• 1. The Interpreter Rule (I)

P-in-L program; L interpreter machine (I) P machine

• 2. The Translator Rule (T)

P-in-S program; S-to-T translator machine (T) P-in-T program

Introduction Interpretation and Translation Interpretation versus Translation Boot Strapping

Displaying a web page

You are given:

• 251 webpage in HTML (HTML program);
• HTML-in-C web browser (HTML-to-display translator

machine);

• C-to-Pentium translator (gcc);
• Pentium-based computer (Pentium interpreter machine).

Using the rules given above, give a “proof” of how to display the 251 webpage

Introduction Interpretation and Translation Interpretation versus Translation Boot Strapping

Displaying a webpage

251 webpage in HTML; HTML-in-C browser; C-to-Pentium translator (T) HTML-in-Pentium browser ; Pentium computer (I) HTML-browser machine (T) Display of 251 webpage

Introduction Interpretation and Translation Interpretation versus Translation Boot Strapping

Translators can compose

introduction.tex

❄ L

AT

EX

introduction.dvi

❄ dvips

introduction.ps ; Postscript printer

(T)

print document

Introduction Interpretation and Translation Interpretation versus Translation Boot Strapping

Alternatively

introduction.tex

❄ L

AT

EX

introduction.dvi

❄ dvips

introduction.ps

✲ ps2pdf

introduction.pdf ; Acrobat reader

(T)

display document

Introduction Interpretation and Translation Interpretation versus Translation Boot Strapping

Pluses and minuses

INTERPRETATION:

• On the fly;
• incremental;
• can be

inefficient.

Introduction Interpretation and Translation Interpretation versus Translation Boot Strapping

Pluses and minuses

INTERPRETATION:

• On the fly;
• incremental;
• can be

inefficient. TRANSLATION:

• Entire

program seen in advance;

• analysis →

efficient;

Introduction Interpretation and Translation Interpretation versus Translation Boot Strapping

Pluses and minuses

INTERPRETATION:

• On the fly;
• incremental;
• can be

inefficient. BYTE-CODE:

• Combines

translation & interpreta- tion;

• portable;
• less efficient

than native code. TRANSLATION:

• Entire

program seen in advance;

• analysis →

efficient;

Introduction Interpretation and Translation Interpretation versus Translation Boot Strapping

Metacircular Interpreters

Scheme-interpreter-in-Scheme; Scheme interpreter machine 1 (I) Scheme interpreter machine 2

Introduction Interpretation and Translation Interpretation versus Translation Boot Strapping

Watch closely

C-to-Pentium-translator-in-C; C-to-Pentium-translator-in-Pentium-1; Pentium machine (I) C-to-Pentium-translator-1 (T) C-to-Pentium-translator-in-Pentium-2

Introduction Interpretation and Translation Interpretation versus Translation Boot Strapping

Nothing up my sleeve

C-to-Pentium-translator-in-C; C-to-Pentium-translator-in-Pentium-1; Pentium machine (I) C-to-Pentium-translator-1 (T) C-to-Pentium-translator-in-Pentium-2 ; Pentium machine (I) C-to-Pentium-translator-2

Introduction Interpretation and Translation Interpretation versus Translation Boot Strapping

Hocus Pocus

C-to-Pentium-trans-in-C; C-to-Pentium-trans-in-C; C-to-Pentium-trans-in-Pentium-1; Pentium machine (I) C-to-Pentium trans-1 (T) C-to-Pentium-translator-in-Pentium-2 ; Pentium machine (I) C-to-Pentium translator-2 (T) C-to-Pentium-in-Pentium translator-3