A single pass assembler scans the program only once and creates the equivalent binary program. The assembler substitute all of the symbolic instruction with machine code in one pass.
A single pass assembler scans the program only once and creates the equivalent binary program. The assembler substitute all of the symbolic instruction with machine code in one pass.
This is about a topic of compiler design, LR and SLR parsing algorithm and LR grammar, Canonical collection and Item, Conflict in LR parsing shift reduce. Classification of Bottom up parsing.
This is a presentation on LALR parser. This presentation was created by 6th sem CSE student.
LALR parser is basically used to creating the LR parsing table. LALR parser is used because it is more powerful than SLR and the tables generated by LALR consumes less memory and disk space than CLR parser.
Assembler is a kind of system software that translate mnemonic codes written in assembly language (which is, in turn, a low-level language) into its equivalent object code (which is, in turn, need to change into executable code by loader and linker)
We have learnt that any computer system is made of hardware and software.
The hardware understands a language, which humans cannot understand. So we write programs in high-level language, which is easier for us to understand and remember.
These programs are then fed into a series of tools and OS components to get the desired code that can be used by the machine.
This is known as Language Processing System.
FellowBuddy.com is an innovative platform that brings students together to share notes, exam papers, study guides, project reports and presentation for upcoming exams.
We connect Students who have an understanding of course material with Students who need help.
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This is about a topic of compiler design, LR and SLR parsing algorithm and LR grammar, Canonical collection and Item, Conflict in LR parsing shift reduce. Classification of Bottom up parsing.
This is a presentation on LALR parser. This presentation was created by 6th sem CSE student.
LALR parser is basically used to creating the LR parsing table. LALR parser is used because it is more powerful than SLR and the tables generated by LALR consumes less memory and disk space than CLR parser.
Assembler is a kind of system software that translate mnemonic codes written in assembly language (which is, in turn, a low-level language) into its equivalent object code (which is, in turn, need to change into executable code by loader and linker)
We have learnt that any computer system is made of hardware and software.
The hardware understands a language, which humans cannot understand. So we write programs in high-level language, which is easier for us to understand and remember.
These programs are then fed into a series of tools and OS components to get the desired code that can be used by the machine.
This is known as Language Processing System.
FellowBuddy.com is an innovative platform that brings students together to share notes, exam papers, study guides, project reports and presentation for upcoming exams.
We connect Students who have an understanding of course material with Students who need help.
Benefits:-
# Students can catch up on notes they missed because of an absence.
# Underachievers can find peer developed notes that break down lecture and study material in a way that they can understand
# Students can earn better grades, save time and study effectively
Our Vision & Mission – Simplifying Students Life
Our Belief – “The great breakthrough in your life comes when you realize it, that you can learn anything you need to learn; to accomplish any goal that you have set for yourself. This means there are no limits on what you can be, have or do.”
Like Us - https://www.facebook.com/FellowBuddycom
Pros and cons of c as a compiler languageAshok Raj
Computer system is made of hardware and software .The hardware understands instructions in the form of electronic charge or binary language in Software programming. So the programs written in High Level Language are fed into a series of tools and OS components to get the desired machine language.This is known as Language Processing System.
LF Energy Webinar: Electrical Grid Modelling and Simulation Through PowSyBl -...DanBrown980551
Do you want to learn how to model and simulate an electrical network from scratch in under an hour?
Then welcome to this PowSyBl workshop, hosted by Rte, the French Transmission System Operator (TSO)!
During the webinar, you will discover the PowSyBl ecosystem as well as handle and study an electrical network through an interactive Python notebook.
PowSyBl is an open source project hosted by LF Energy, which offers a comprehensive set of features for electrical grid modelling and simulation. Among other advanced features, PowSyBl provides:
- A fully editable and extendable library for grid component modelling;
- Visualization tools to display your network;
- Grid simulation tools, such as power flows, security analyses (with or without remedial actions) and sensitivity analyses;
The framework is mostly written in Java, with a Python binding so that Python developers can access PowSyBl functionalities as well.
What you will learn during the webinar:
- For beginners: discover PowSyBl's functionalities through a quick general presentation and the notebook, without needing any expert coding skills;
- For advanced developers: master the skills to efficiently apply PowSyBl functionalities to your real-world scenarios.
Epistemic Interaction - tuning interfaces to provide information for AI supportAlan Dix
Paper presented at SYNERGY workshop at AVI 2024, Genoa, Italy. 3rd June 2024
https://alandix.com/academic/papers/synergy2024-epistemic/
As machine learning integrates deeper into human-computer interactions, the concept of epistemic interaction emerges, aiming to refine these interactions to enhance system adaptability. This approach encourages minor, intentional adjustments in user behaviour to enrich the data available for system learning. This paper introduces epistemic interaction within the context of human-system communication, illustrating how deliberate interaction design can improve system understanding and adaptation. Through concrete examples, we demonstrate the potential of epistemic interaction to significantly advance human-computer interaction by leveraging intuitive human communication strategies to inform system design and functionality, offering a novel pathway for enriching user-system engagements.
Dev Dives: Train smarter, not harder – active learning and UiPath LLMs for do...UiPathCommunity
💥 Speed, accuracy, and scaling – discover the superpowers of GenAI in action with UiPath Document Understanding and Communications Mining™:
See how to accelerate model training and optimize model performance with active learning
Learn about the latest enhancements to out-of-the-box document processing – with little to no training required
Get an exclusive demo of the new family of UiPath LLMs – GenAI models specialized for processing different types of documents and messages
This is a hands-on session specifically designed for automation developers and AI enthusiasts seeking to enhance their knowledge in leveraging the latest intelligent document processing capabilities offered by UiPath.
Speakers:
👨🏫 Andras Palfi, Senior Product Manager, UiPath
👩🏫 Lenka Dulovicova, Product Program Manager, UiPath
Welocme to ViralQR, your best QR code generator.ViralQR
Welcome to ViralQR, your best QR code generator available on the market!
At ViralQR, we design static and dynamic QR codes. Our mission is to make business operations easier and customer engagement more powerful through the use of QR technology. Be it a small-scale business or a huge enterprise, our easy-to-use platform provides multiple choices that can be tailored according to your company's branding and marketing strategies.
Our Vision
We are here to make the process of creating QR codes easy and smooth, thus enhancing customer interaction and making business more fluid. We very strongly believe in the ability of QR codes to change the world for businesses in their interaction with customers and are set on making that technology accessible and usable far and wide.
Our Achievements
Ever since its inception, we have successfully served many clients by offering QR codes in their marketing, service delivery, and collection of feedback across various industries. Our platform has been recognized for its ease of use and amazing features, which helped a business to make QR codes.
Our Services
At ViralQR, here is a comprehensive suite of services that caters to your very needs:
Static QR Codes: Create free static QR codes. These QR codes are able to store significant information such as URLs, vCards, plain text, emails and SMS, Wi-Fi credentials, and Bitcoin addresses.
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Pricing and Packages
Additionally, there is a 14-day free offer to ViralQR, which is an exceptional opportunity for new users to take a feel of this platform. One can easily subscribe from there and experience the full dynamic of using QR codes. The subscription plans are not only meant for business; they are priced very flexibly so that literally every business could afford to benefit from our service.
Why choose us?
ViralQR will provide services for marketing, advertising, catering, retail, and the like. The QR codes can be posted on fliers, packaging, merchandise, and banners, as well as to substitute for cash and cards in a restaurant or coffee shop. With QR codes integrated into your business, improve customer engagement and streamline operations.
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Subscribers of ViralQR receive detailed analytics and tracking tools in light of having a view of the core values of QR code performance. Our analytics dashboard shows aggregate views and unique views, as well as detailed information about each impression, including time, device, browser, and estimated location by city and country.
So, thank you for choosing ViralQR; we have an offer of nothing but the best in terms of QR code services to meet business diversity!
Le nuove frontiere dell'AI nell'RPA con UiPath Autopilot™UiPathCommunity
In questo evento online gratuito, organizzato dalla Community Italiana di UiPath, potrai esplorare le nuove funzionalità di Autopilot, il tool che integra l'Intelligenza Artificiale nei processi di sviluppo e utilizzo delle Automazioni.
📕 Vedremo insieme alcuni esempi dell'utilizzo di Autopilot in diversi tool della Suite UiPath:
Autopilot per Studio Web
Autopilot per Studio
Autopilot per Apps
Clipboard AI
GenAI applicata alla Document Understanding
👨🏫👨💻 Speakers:
Stefano Negro, UiPath MVPx3, RPA Tech Lead @ BSP Consultant
Flavio Martinelli, UiPath MVP 2023, Technical Account Manager @UiPath
Andrei Tasca, RPA Solutions Team Lead @NTT Data
SAP Sapphire 2024 - ASUG301 building better apps with SAP Fiori.pdfPeter Spielvogel
Building better applications for business users with SAP Fiori.
• What is SAP Fiori and why it matters to you
• How a better user experience drives measurable business benefits
• How to get started with SAP Fiori today
• How SAP Fiori elements accelerates application development
• How SAP Build Code includes SAP Fiori tools and other generative artificial intelligence capabilities
• How SAP Fiori paves the way for using AI in SAP apps
The Art of the Pitch: WordPress Relationships and SalesLaura Byrne
Clients don’t know what they don’t know. What web solutions are right for them? How does WordPress come into the picture? How do you make sure you understand scope and timeline? What do you do if sometime changes?
All these questions and more will be explored as we talk about matching clients’ needs with what your agency offers without pulling teeth or pulling your hair out. Practical tips, and strategies for successful relationship building that leads to closing the deal.
GraphRAG is All You need? LLM & Knowledge GraphGuy Korland
Guy Korland, CEO and Co-founder of FalkorDB, will review two articles on the integration of language models with knowledge graphs.
1. Unifying Large Language Models and Knowledge Graphs: A Roadmap.
https://arxiv.org/abs/2306.08302
2. Microsoft Research's GraphRAG paper and a review paper on various uses of knowledge graphs:
https://www.microsoft.com/en-us/research/blog/graphrag-unlocking-llm-discovery-on-narrative-private-data/
Generative AI Deep Dive: Advancing from Proof of Concept to ProductionAggregage
Join Maher Hanafi, VP of Engineering at Betterworks, in this new session where he'll share a practical framework to transform Gen AI prototypes into impactful products! He'll delve into the complexities of data collection and management, model selection and optimization, and ensuring security, scalability, and responsible use.
Generative AI Deep Dive: Advancing from Proof of Concept to Production
Compiler Design(NANTHU NOTES)
1. PRINCIPLE OF COMPILER DESIGN
TRANSLATOR
A translator is a program that takes as input a program written in one language and
produces as output a program in another language. Beside program translation, the translator
performs another very important role, the error-detection. Any violation of d HLL specification
would be detected and reported to the programmers. Important role of translator are:
1, translating the HLL program input into an equivalent ML program.
2, providing diagnostic messages wherever the programmer violates specification of the
HLL.
TYPE OF TRANSLATORS:-
• INTERPRETOR
• COMPILER
• PREPROSSESSOR
COMPILER (5 MARKS) :-
Compiler is a translator program that translates a program written in (HLL) the source
program and translate it into an equivalent program in (MLL) the target program. As an important
part of a compiler is error showing to the programmer.
Source pgm target pgm
Compiler
Error msg
Executing a program written n HLL programming language is basically of two parts. the source
program must first be compiled translated into a object program. Then the results object program
is loaded into a memory executed.
Source pgm obj pgm
compiler
Obj pgm input opj pgm output
Obj pgm
1
2. STRUCTURE OF THE COMPILER DESIGN (10 MARKS):-
Compilation process is partitioned into no-of-sub processes called ‘phases’.
Source Program
Lexical Analyzer
Token
Syntax Analyzer
Parse Tree
Table Intermediate code G Error Handling
Management
Intermediate Code
Code Optimization
Improved IMC
Code Generation
Target Program
Lexical Analysis:-
LA or Scanners reads the source program one character at a time, carving the
source program into a sequence of automic units called tokens.
Syntax Analysis:-
The second stage of translation is called Syntax analysis or parsing. In this phase
expressions, statements, declarations etc… are identified by using the results of lexical analysis.
Syntax analysis is aided by using techniques based on formal grammar of the programming
language.
Intermediate Code Generations:-
An intermediate representation of the final machine language code is produced.
This phase bridges the analysis and synthesis phases of translation.
Code Optimization :-
This is optional phase described to improve the intermediate code so that the
output runs faster and takes less space.
Code Generation:-
The last phase of translation is code generation. A number of optimizations to
reduce the length of machine language program are carried out during this phase. The output
of the code generator is the machine language program of the specified computer.
Table Management (or) Book-keeping:-
This is the portion to keep the names used by the program and records essential
information about each. The data structure used to record this information called a ‘Symbol
Table’.
Error Handlers:-
It is invoked when a flaw error in the source program is detected.
2
3. Passes:-
One (or) more phases one combined into a module called a pass.
Single-pass Compiler:-
All the phases are combined into a single
Multi-pass Compiler:-
More than one phase are combined into a number of groups called multi-pass.
(Multi pass compiler can be made to use less space than single pass compiler.).
TOKEN (5 MARKS) :-
LA reads the source program one character at a time, carving the source program into a
sequence of automatic units called ‘Tokens’.
1, Type of the token. 2, Value of the token.
Type : variable, operator, keyword, constant
Value : N1ame of variable, current variable (or) pointer to symbol table.
If the symbols given in the standard format the LA accepts and produces
token as output. Each token is a sub-string of the program that is to be treated as a single unit.
Token are two types.
1, Specific strings such as IF (or) semicolon.
2, Classes of string such as identifiers, label, constants.
STRUCTURE OF THE COMPILER DESIGN (20 MARKS) :-
Theoutput of LA is a stream of tokens, which is passed to the next phase, the
syntax analyzer or parser. The SA groups the tokens together into syntactic structure called as
expression. Expression may further be combined to form statements. The syntactic structure can
be regarded as a tree whose leaves are the token called as parse trees.
The parser has two functions. It checks if the tokens from lexical analyzer, occur
in pattern that are permitted by the specification for the source language. It also imposes on
tokens a tree-like structure that is used by the sub-sequent phases of the compiler.
Example, if a program contains the expression A+/B after lexical analysis this
expression might appear to the syntax analyzer as the token sequence id+/id. On seeing the /, the
syntax analyzer should detect an error situation, because the presence of these two adjacent
binary operators violates the formulations rule of an expression.
Syntax analysis is to make explicit the hierarchical structure of the incoming token
stream by identifying which parts of the token stream should be grouped.
Example, (A/B*C has two possible interpretations.)
1, divide A by B and then multiply by C or
2, multiply B by C and then use the result to divide A.
each of these two interpretations can be represented in terms of a parse tree.
Intermediate Code Generation:-
The intermediate code generation uses the structure produced by the syntax
analyzer to create a stream of simple instructions. Many styles of intermediate code are possible.
One common style uses instruction with one operator and a small number of operands.
3
4. The output of the syntax analyzer is some representation of a parse tree. the
intermediate code generation phase transforms this parse tree into an intermediate language
representation of the source program.
Code Optimization (5 MARKS) :-
This is optional phase described to improve the intermediate code so that the
output runs faster and takes less space. Its output is another intermediate code program that does
the some job as the original, but in a way that saves time and / or spaces.
1, Local Optimization:-
There are local transformations that can be applied to a program to make
an improvement. For example,
If A > B goto L2
Goto L3
L2 :
This can be replaced by a single statement
If A < B goto L3
Another important local optimization is the elimination of common sub-
expressions
A := B + C + D
E := B + C + F
Might be evaluated as
T1 := B + C
A := T1 + D
E := T1 + F
Take this advantage of the common sub-expressions B + C.
2, Loop Optimization:-
Another important source of optimization concerns about increasing the
speed of loops. A typical loop improvement is to move a computation
that produces the same result each time around the loop to a point, in the
program just before the loop is entered.
Code generator :-
Cg produces the object code by deciding on the memory locations for data,
selecting code to access each datum and selecting the registers in which each computation is to be
done. Many computers have only a few high speed registers in which computations can be
performed quickly. A good code generator would attempt to utilize registers as efficiently as
possible.
Table Management OR Book-keeping :-
A compiler needs to collect information about all the data objects that appear in
the source program. The information about data objects is collected by the early phases of the
compiler-lexical and syntactic analyzers. The data structure used to record this information is
called as Symbol Table.
Error Handing :-
One of the most important functions of a compiler is the detection and reporting of
errors in the source program. The error message should allow the programmer to determine
exactly where the errors have occurred. Errors may occur in all or the phases of a compiler.
4
5. Whenever a phase of the compiler discovers an error, it must report the error to the
error handler, which issues an appropriate diagnostic msg. Both of the table-management and
error-Handling routines interact with all phases of the compiler.
Position:= initial + rate *60
Lexical Analyzer
Tokens id1 = id2 + id3 * id4
Syntsx Analyzer
=
id1 +
id2 *
id3 id4
Semantic Analyzer
=
id1 +
id2 *
id3 60
int to real
Intermediate Code Generator
temp1:= int to real (60)
temp2:= id3 * temp1
temp3:= id2 + temp2
id1:= temp3.
Code Optimizer
5
6. Temp1:= id3 * 60.0
Id1:= id2 +temp1
Code Generator
MOVF id3, r2
MULF *60.0, r2
MOVF id2, r2
ADDF r2, r1
MOVF r1, id1
PARSER (5 MARKS) :-
syntactic structure can be regarded as a tree whose leaves are the token called as
parse trees, also called syntax analyzer and grammar.
The main purpose is to evaluate which statement will execute first, also parse
tells how do we calculate. The parser has two functions. It checks if the tokens from lexical
analyzer, occur in pattern that are permitted by the specification for the source language. It also
imposes on tokens a tree-like structure that is used by the sub-sequent phases of the compiler.
Example, A/B*C has two possible interpretations:
1, divide A by B and then multiply by C or
2, multiply B by C and then use the result to divide A.
expression expression
exp exp exp exp
exp exp
exp exp
A / B * C A / B * C
Each of these two interpretations can be represented in terms of a parse
tree, a diagram, which exhibits the syntactic structure of the expression.
Parse tree and derivations:-
6
7. Each interior node of a parse tree is labeled by some non-terminal A, and that
the children of the node are labeled, from left to right, by the symbols in the right side of
the production by which this A was replaced in the derivation.
PARSER (SHORT NOTE) (5 MARKS) :-
• A parser for grammar G is a program that takes as input a string W and
produces as output either a parse tree for W, if W is a sentence of G, or
an error message indicating that W is not a sentence of G.
• Two basic types of parsers for context-free grammars are bottom-
up and top-down. Bottom – up parsers build parse trees from the
bottom (leaves) to the top (root), while top-down parsers start with the
root and work down to the leaves. In both cases the input to the parser is
being scanned from left to right, one symbol at a time.
Representation of a Parse Tree,
There are two basic types of representation of a parse tree implicit and
explicit. The sequence of production used in some derivation is an example of an implicit
representation. A linked structure for the parse tree is an explicit representation.
TOP-DOWN PARSING (5 MARKS) :-
• We first discuss a general form of top down parsing that may involve
backtracking, that is making repeated scans of the input. We then
discuss a special case, called recursive-descent parsing, which
eliminates the need for backtracking over the input.
• Top down parsing can be viewed as an attempt to find a leftmost
derivation for an input string. Equivalently, it can be viewed as
attempting to construct a parse tree for the input starting from the root
and creating the nodes of the parse tree in preorder.
• There are several difficulties with top down parsing. First is left
recursion. Second problem is top down parsing is backtracking. If
we make a sequence of erroneous expansions and subsequently discover
a mismatch, we may have to undo the semantic effects of making these
erroneous expansions.
• The third problem with top down backtracking parsers is that, the
order in which alternates are tried can affect the language accepted. For
example,
S
c A d
7
8. a
• yet another problem is that when failure is reported, we have very little
idea where the error actually occurred. In the form given here, top down
parser with backtrack simply returns failure no matter what the error is.
SHIFT REDUCE PARSING (5 MARKS) :-
This parsing method is bottom up because it attempts to construct a parse tree for an input
string beginning at the leaves (Bottom) and working up towards the root (the Top). This
process is one that ‘reduces’ a string W to the start symbol of a grammar. At each step a
string matching the right side of a production is replaced by the symbol on the left. There
are four types of action performed in shift reduce parsing.
1, Shift :- the symbol is shifted to the top of the stack.
2, Reduce :- the parser knows the right end of the handle is at the top of
the stack.
3, Accept :- it must then locate the left end of the handle with in the stack
and device with what non-terminal to replace the handle.
4, Error :- the parser discovers that a syntax error has occurred and calls
in error recovery routine.
Stack implementation of Shift Reduce Parsing (SRP):-
There are 2 problems that must be solved if we are to automate parse by handle
pruning. The first is how to locate a handle in a right-sentential form, and the second is
what production to choose in case there is more than one production with the same right
side.
A convenient way to implement a SRP is to use a stack and an input buffer. We
shall use $ to mark the bottom of the stack and the right end of the input.
Stack output
$ w$
LEXICAL ANALYZER (10 MARKS) :-
1, to identify the tokens we need some method of describing the possible tokens
that can appear in the input stream. For this purpose we introduce regular expression, a
notation that can be used to describe essentially all the tokens of programming language.
2, secondly, having decided what the tokens are, we need some mechanism to
recognize these in the input stream. This is done by the token recognizers, which are
designed using transition diagrams and finite automata.
Role of Lexical Analyzer,
the LA is the first phase of a compiler. It main task is to read the input character
and produce as output a sequence of tokens that the parser uses for syntax analysis.
diagram area
8
9. Upon receiving a ‘get next token’ command form the parser, the lexical
analyzer reads the input character until it can identify the next token. The LA return to
the parser representation for the token it has found. The representation will be an integer
code, if the token is a simple construct such as parenthesis, comma or colon.
LA may also perform certain secondary tasks as the user interface. One such
task is striping out from the source program the commands and white spaces in the form
of blank, tab and new line characters. Another is correlating error message from the
compiler with the source program.
Input Buffering,
The LA scans the characters of the source pgm one at a time to discover tokens.
Because of large amount of time can be consumed scanning characters, specialized
buffering techniques have been developed to reduce the amount of overhead required to
process an input character.
Regular expressions (5 MARKS) :-
Regular expression is a formula that describes a possible set of string.
Component of regular expression..
X the character x
. any character, usually accept a new line
[x y z] any of the characters x, y, z, …..
R? a R or nothing (=optionally as R)
R* zero or more occurrences…..
R+ one or more occurrences ……
R1R2 an R1 followed by an R2
R2R1 either an R1 or an R2.
A token is either a single string or one of a collection of strings of a certain type. If we
view the set of strings in each token class as an language, we can use the regular-
expression notation to describe tokens.
Consider an identifier, which is defined to be a letter followed by zero or more letters or
digits. In regular expression notation we would write.
Identifier = letter (letter | digit)*
Here are the rules that define the regular expression over alphabet .
o is a regular expression denoting { € }, that is, the language containing
only the empty string.
o For each ‘a’ in ∑, is a regular expression denoting { a }, the language
with only one string consisting of the single symbol ‘a’ .
o If R and S are regular expressions, then
9
10. (R) | (S) means LrULs
R.S means Lr.Ls
R* denotes Lr*
Regular Definitions (5 MARKS) :-
For notational convenience, we may wish to give names to regular expressions
and to define regular expressions using these names as if they were symbols.
Identifiers are the set or string of letters and digits beginning with a letter. The
following regular definition provides a precise specification for this class of string.
Example-1,
Ab*|cd? Is equivalent to (a(b*)) | (c(d?))
Pascal identifier
Letter - A | B | ……| Z | a | b |……| z|
Digits - 0 | 1 | 2 | …. | 9
Id - letter (letter / digit)*
Transition Diagrams (5 MARKS) :-
As an intermediate step in the construction of a LA, we first produce a stylized
flowchart, called a transition diagram. Position in a transition diagram, are drawn as
circles and are called as states.
Picture area
The above TD for an identifier, defined to be a letter followed by any no of
letters or digits.
A sequence of transition diagram can be converted into program to look for the tokens
specified by the diagrams. Each state gets a segment of code.
If = if
Then = then
Else = else
Relop = < | <= | = | > | >=
Id = letter (letter | digit) *|
Num = digit |
10
11. AUTOMATA
An automation is defined as a system where information is transmitted and used for
performing some functions without direct participation of man.
1, an automation in which the output depends only on the input is called an automation
without memory.
2, an automation in which the output depends on the input and state also is called as
automation with memory.
3, an automation in which the output depends only on the state of the machine is called a
Moore machine.
3, an automation in which the output depends on the state and input at any instant of time
is called a mealy machine.
Description of Automata
1, an automata has a mechanism to read input from input tape,
2, any language is recognized by some automation, Hence these automation are basically
language ‘acceptors’ or ‘language recognizers’.
Types of Finite Automata
• Deterministic Automata
• Non-Deterministic Automata.
DETERMINISTIC AUTOMATA
A deterministic finite automata has at most one transition from each state on any input. A
DFA is a special case of a NFA in which:-
1, it has no transitions on input € ,
2, each input symbol has at most one transition from any state.
DFA formally defined by 5 tuple notation M = (Q, ∑, δ, qo, F), where
Q is a finite ‘set of states’, which is non empty.
∑ is ‘input alphabets’, indicates input set.
qo is an ‘initial state’ and qo is in Q ie, qo, ∑, Q
F is a set of ‘Final states’,
δ is a ‘transmission function’ or mapping function, using this function the next
state can be determined.
The regular expression is converted into minimized DFA by the following procedure:
11
12. Regular expression → NFA → DFA → Minimized DFA
The Finite Automata is called DFA if there is only one path for a specific input from
current state to next state.
a
a
S S2
o
b
S
1
From state S0 for input ‘a’ there is only one path going to S2. similarly from S0 there is
only one path for input going to S1.
NONDETERMINISTIC AUTOMATA
• A NFA is a mathematical model that consists of
A set of states S.
A set of input symbols ∑.
A transition for move from one state to an other.
A state so that is distinguished as the start (or initial) state.
A set of states F distinguished as accepting (or final) state.
A number of transition to a single symbol.
• A NFA can be diagrammatically represented by a labeled
directed graph, called a transition graph, In which the nodes are
the states and the labeled edges represent the transition function.
• This graph looks like a transition diagram, but the same
character can label two or more transitions out of one state and
edges can be labeled by the special symbol € as well as by input
symbols.
• The transition graph for an NFA that recognizes the language ( a
| b ) * abb is shown
12
13. Picture area
Transition Table
• When describing an NFA, we use the transition graph representation. In
computer, the transition function of an NFA can be implemented in several
different ways. The easiest implementation in a transition table is which there is a
row for each state and a column for each input symbol and € , if necessary.
• The transition table representation has the advantage that it provides fast access
to the transitions of a given state on a given character; its advantage is that it can
take up a lot of space when the input alphabet is large and most transitions are to
the empty set.
CREATING NFA AND DFA
Construction of an NFA from a regular expression
Conversion of NFA into a DFA
Regular expression to NFA
Regular expression r= (a | b)*abb
Step-1
Picture area
Step-2
,, ,,
Step-3
,, ,,
13
15. DEFINITION OF CFG
It involves four quantities.
CFG contain terminals, N-T, start symbol and production.
• Terminal are basic symbols form which string are formed.
• N-terminals are synthetic variables that denote sets of strings
• In a Grammar, one N-T are distinguished as the start symbol, and the set of string
it denotes is the language defined by the grammar.
• The production of the grammar specify the manor in which the terminal and N-T
can be combined to form strings.
• Each production consists of a N-T, followed by an arrow, followed by a string of
one terminal and terminals.
DEFINITION OF SYMBOL TABLE
• An extensible array of records.
• The identifier and the associated records contains collected information about the
identifier.
FUNCTION identify (Identifier name)
RETURNING a pointer to identifier
Identifier information contains
• The actual string
• A macro definition
• A keyword definition
• A list of type, variable & function definition
• A list of structure and union name definition
• A list of structure and union field selected definitions.
I will give the topics and important sub-topics following only two
questions,
It can understand at anybody.
But this short topics is not enough to us, so please read the entire page.
My points of view I didn’t do any error in this content, if you find any
please correct it…….
15
16. BY……
NANTHA KUMAR S.R
Mathu321nanthu@gmail.com
9362740520
TRANSLATOR
1. it is a program
2. it has two work
a. convert a program form one language to another
b. find and report the error to the user
COMPILER
1. it is a translator program.
2. it has two main works:-(already we know)
3. two main part besides execute a program
a. source program compiled and translate into a object
program.
b. Result(object program) is load for executed.
STRUCTURE OF COMPILER DESIGN
Lexical Analyzer:-
1. read the source program.
2. cut the source program into a sequence of units called
token.
Syntax Analyzer
1. expression, statement and declarations are identified
2. it has some grammar to do this work.
IMG
1. in this phase intermediate code generated. but not
cleared,
2. because it has lot of empty spaces and lines
16
17. code optimization
1. improve the intermediate code(ignore waste line and
space)
2. so program run fast with less space.
STRUCTURE OF COMPILER DESIGN
1. lexical analyzer read a source program and produce
output as a tokens
2. syntax analyzer group that tokens like synthetic structure
3. this syntax analyzer can be regarded as a tree, it is called
a parse tree.
Parser has two functions:-
A. check the token.
B. Impose the token as a tree.
Sweeet and cute example- (1):
A+/b it is one expression
1, lexical analyzer read it and produce a token. (because it is not
a error in lexical analyzer point of view)
2, but syntax analyzer told that it is error. (because two binary
operator is near by near)
Sweeet and cute example- (1):
1. syntax analyzer normally make a detailed structure
of the incoming tokens
2. why ?
3. because next step person(IMG) can identify very
quickly.
A/B*C
a. it can divide A by B then multiply by C
b. multiply B by C then use the result to divide
A.
next step person (IMG) can identify quickly that, which group
may I take now.
CODE OPTIMIZATION
1. read the IMG.
2. take some cutting and joining work I mean(reduce the
empty space and line).
3. two main function can do this work.
17
18. a. Local optimization
b. Loop opotimization
PARSER
Two main purpose of parser:
a. Decide which statement will execute first
b. How do we calculate
LEXICAL ANALYZER
It has two main components
1. regular expression
2. token recognizer
two tools to use to construct the token recognizer.
a. transition diagram
b. finite automata.
(please write all the topics briefly, if they ask it on 20 marks questions)
18
19. IMPORTANT QUESTIONS
20 MARKS:
1. details about lexical analyzer
2. state minimization of DFA
3. NFA-DFA
4. DAG algorithm
5. Boolean expression
6. storage allocation(Dynamic)
7. overloaded function and operator
5 (or) 10 MARKS
1. polymorphic function
2. back parching
3. bottom up parsing
4. top town parsing
5. shift reduce parsing
6. lexical analyzer
7. LA-LR parser
8. parser tree (or) generator (or) parameter
9. YACC
10.global data analyzer.
11.regular expression
12.symbol table or code optimization
many more questions I couldn’t take notes now, also it is in out
book very easily, because already I read it.
19