Syntax analysis is the second phase of compiler design after lexical analysis. The parser checks if the input string follows the rules and structure of the formal grammar. It builds a parse tree to represent the syntactic structure. If the input string can be derived from the parse tree using the grammar, it is syntactically correct. Otherwise, an error is reported. Parsers use various techniques like panic-mode, phrase-level, and global correction to handle syntax errors and attempt to continue parsing. Context-free grammars are commonly used with productions defining the syntax rules. Derivations show the step-by-step application of productions to generate the input string from the start symbol.
In this slide you will explore more about how to make derivations ,design parse tree ,what is ambiguity and how to remove ambiguity ,left recursion ,left factoring .
In this slide you will explore more about how to make derivations ,design parse tree ,what is ambiguity and how to remove ambiguity ,left recursion ,left factoring .
match the following attributes to the parts of a compilerstrips ou.pdfarpitaeron555
match the following attributes to the parts of a compiler
strips out the comments and whitespace
converts text into lexemes
generates an Abstrat Symbol Tree
recursive descent or table driven
uses BNF or EBNF definitions
a. lexer
b. parser
Solution
The Program and Portfolio Management Maturity Model is an effective tool for organizations to
decide quickly what PPM improvements they should make to enhance their organization\'s
ability to optimize investments, execute big changes and deliver value.
Overview
Key Findings
Real project, program and portfolio management, when operating at the level of well-integrated
practices, is the key enabler that allows organizations to identify and execute strategic change.
Any meaningful undertakings to enhance or evolve the program and portfolio management
(PPM) function must pay more than lip service to organizational structure, business model and
culture to have any chance of success.
Competitive pressures and changing market conditions are forcing organizations toward Level 3,
and most organizations still aren\'t ready to make the leap.
Recommendations
At any level of PPM maturity, focus first on helping the organization make well-informed
investment choices. This will improve the odds of project success more than any other factor.
For organizations that require enterprisewide change and capabilities, it is worth the effort to
pursue Level 4, where enterprise PPM practices are built.
Identify objectives for your enterprise, and use them to identify the most salient improvement
opportunities for your enterprise.
Meticulously manage the change involved in maturing/improving your PPM capabilities.
Analysis
Project/program/portfolio management office (PMO) leaders, program managers and portfolio
managers are frequently challenged by ineffective processes, lack of stakeholder engagement and
difficult-to-quantify value. 1 Part of the problem is failure to match their processes, people and
technology approaches to the maturity level of their organizations. 2
The Gartner Program and Portfolio Management (PPM) Maturity Model assessment is designed
to help PPM leaders understand best practices around large project management, as well as PPM
to handle delivery of strategic value. This model assumes that organizations progress through a
maturity curve and that each level of organizational maturity directly affects the level of
investment and types of PPM approaches organizations choose to adopt.
arsing
A parser is an algorithm that determines whether a given input string is in a language and, as a
side-effect, usually produces a parse tree for the input. There is a procedure for generating a
parser from a given context-free grammar.
Recursive-Descent Parsing
Recursive-descent parsing is one of the simplest parsing techniques that is used in practice.
Recursive-descent parsers are also called top-down parsers, since they construct the parse tree
top down (rather than bottom up).
The basic idea of recursive-descent par.
Using recycled concrete aggregates (RCA) for pavements is crucial to achieving sustainability. Implementing RCA for new pavement can minimize carbon footprint, conserve natural resources, reduce harmful emissions, and lower life cycle costs. Compared to natural aggregate (NA), RCA pavement has fewer comprehensive studies and sustainability assessments.
Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
Overview of the fundamental roles in Hydropower generation and the components involved in wider Electrical Engineering.
This paper presents the design and construction of hydroelectric dams from the hydrologist’s survey of the valley before construction, all aspects and involved disciplines, fluid dynamics, structural engineering, generation and mains frequency regulation to the very transmission of power through the network in the United Kingdom.
Author: Robbie Edward Sayers
Collaborators and co editors: Charlie Sims and Connor Healey.
(C) 2024 Robbie E. Sayers
Final project report on grocery store management system..pdfKamal Acharya
In today’s fast-changing business environment, it’s extremely important to be able to respond to client needs in the most effective and timely manner. If your customers wish to see your business online and have instant access to your products or services.
Online Grocery Store is an e-commerce website, which retails various grocery products. This project allows viewing various products available enables registered users to purchase desired products instantly using Paytm, UPI payment processor (Instant Pay) and also can place order by using Cash on Delivery (Pay Later) option. This project provides an easy access to Administrators and Managers to view orders placed using Pay Later and Instant Pay options.
In order to develop an e-commerce website, a number of Technologies must be studied and understood. These include multi-tiered architecture, server and client-side scripting techniques, implementation technologies, programming language (such as PHP, HTML, CSS, JavaScript) and MySQL relational databases. This is a project with the objective to develop a basic website where a consumer is provided with a shopping cart website and also to know about the technologies used to develop such a website.
This document will discuss each of the underlying technologies to create and implement an e- commerce website.
NUMERICAL SIMULATIONS OF HEAT AND MASS TRANSFER IN CONDENSING HEAT EXCHANGERS...ssuser7dcef0
Power plants release a large amount of water vapor into the
atmosphere through the stack. The flue gas can be a potential
source for obtaining much needed cooling water for a power
plant. If a power plant could recover and reuse a portion of this
moisture, it could reduce its total cooling water intake
requirement. One of the most practical way to recover water
from flue gas is to use a condensing heat exchanger. The power
plant could also recover latent heat due to condensation as well
as sensible heat due to lowering the flue gas exit temperature.
Additionally, harmful acids released from the stack can be
reduced in a condensing heat exchanger by acid condensation. reduced in a condensing heat exchanger by acid condensation.
Condensation of vapors in flue gas is a complicated
phenomenon since heat and mass transfer of water vapor and
various acids simultaneously occur in the presence of noncondensable
gases such as nitrogen and oxygen. Design of a
condenser depends on the knowledge and understanding of the
heat and mass transfer processes. A computer program for
numerical simulations of water (H2O) and sulfuric acid (H2SO4)
condensation in a flue gas condensing heat exchanger was
developed using MATLAB. Governing equations based on
mass and energy balances for the system were derived to
predict variables such as flue gas exit temperature, cooling
water outlet temperature, mole fraction and condensation rates
of water and sulfuric acid vapors. The equations were solved
using an iterative solution technique with calculations of heat
and mass transfer coefficients and physical properties.
NO1 Uk best vashikaran specialist in delhi vashikaran baba near me online vas...Amil Baba Dawood bangali
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Cosmetic shop management system project report.pdfKamal Acharya
Buying new cosmetic products is difficult. It can even be scary for those who have sensitive skin and are prone to skin trouble. The information needed to alleviate this problem is on the back of each product, but it's thought to interpret those ingredient lists unless you have a background in chemistry.
Instead of buying and hoping for the best, we can use data science to help us predict which products may be good fits for us. It includes various function programs to do the above mentioned tasks.
Data file handling has been effectively used in the program.
The automated cosmetic shop management system should deal with the automation of general workflow and administration process of the shop. The main processes of the system focus on customer's request where the system is able to search the most appropriate products and deliver it to the customers. It should help the employees to quickly identify the list of cosmetic product that have reached the minimum quantity and also keep a track of expired date for each cosmetic product. It should help the employees to find the rack number in which the product is placed.It is also Faster and more efficient way.
6th International Conference on Machine Learning & Applications (CMLA 2024)ClaraZara1
6th International Conference on Machine Learning & Applications (CMLA 2024) will provide an excellent international forum for sharing knowledge and results in theory, methodology and applications of on Machine Learning & Applications.
Hierarchical Digital Twin of a Naval Power SystemKerry Sado
A hierarchical digital twin of a Naval DC power system has been developed and experimentally verified. Similar to other state-of-the-art digital twins, this technology creates a digital replica of the physical system executed in real-time or faster, which can modify hardware controls. However, its advantage stems from distributing computational efforts by utilizing a hierarchical structure composed of lower-level digital twin blocks and a higher-level system digital twin. Each digital twin block is associated with a physical subsystem of the hardware and communicates with a singular system digital twin, which creates a system-level response. By extracting information from each level of the hierarchy, power system controls of the hardware were reconfigured autonomously. This hierarchical digital twin development offers several advantages over other digital twins, particularly in the field of naval power systems. The hierarchical structure allows for greater computational efficiency and scalability while the ability to autonomously reconfigure hardware controls offers increased flexibility and responsiveness. The hierarchical decomposition and models utilized were well aligned with the physical twin, as indicated by the maximum deviations between the developed digital twin hierarchy and the hardware.
2. Outline
Definition - Role of parser
Lexical versus Syntactic Analysis
Representative Grammars
Syntax Error Handling
Error recovery strategies
Derivations
2
3. What is Syntax Analysis?
Syntax Analysis is a second phase of the compiler design process after lexical
analysis in which the given input string is checked for the confirmation of rules and
structure of the formal grammar.
Syntax Analyzer or Parser analyses the syntactical structure and checks if the
given input is in the correct syntax of the programming language or not.
It does so by getting the input from the tokens and building a data structure, called a
Syntax tree or Parse tree.
3
5. Cont.
The parse tree is constructed by using the pre-defined Grammar of the language and
the input string.
If the given input string can be produced with the help of the syntax tree, then the
input string is found to be in the correct syntax.
Otherwise, error is reported by syntax analyzer.
5
7. Tasks performed by Parser
The parser helps to apply rules to the code
Helps to make sure that each opening brace has a corresponding closing balance
Helps to detect all types of Syntax errors
Find the position at which error has occurred
Clear and accurate description of the error
Recovery from an error to continue and find further errors in the code
Should not affect compilation of “correct” programs
The parse must reject invalid texts by reporting syntax errors
7
8. Types of Parsers
Three types:
Universal Parser
Top-down Parser
Bottom-up Parser
Universal Parsers like CYK (Cocke-Younger-Kasami) algorithm and Earley’s
Algorithm can parse any grammar but they are inefficient to use in production
compilers.
As implied by their names, top-down parsers build parse trees from the top (root) to
the bottom (leaves). Eg. LL parser
Bottom-up parsers start from the leaves and work their way up to the root. Eg. LR
parser
8
9. Syntax Error Handling
Types of Errors
1) Lexical
2) Syntactic
3) Semantic
4) Logical
Lexical errors include misspellings of identiers, keywords, or
operators.
e.g., the use of an identier elipseSize instead of ellipseSize
missing quotes around text intended as a string
Syntactic errors include misplaced semicolons or extra or
missing braces; that is, “{”or “}”
Example: In C or Java, the appearance of a case statement without
an enclosing switch is a syntactic error
9
10. Syntax Error Handling
Types of Errors
1) Lexical
2) Syntactic
3) Semantic
4) Logical
Semantic errors include type mismatches between operators and
operands,
e.g., the return of a value in a Java method with result type void.
Logical errors occur when executed code does not produce the
expected result.
incorrect reasoning on the part of the programmer
The use in a C program of the assignment operator = instead of the
comparison operator = =
10
11. Syntax Error Handling
The error handler in a parser has goals that are simple to state but
challenging to realize:
Report the presence of errors clearly and accurately.
Recover from each error quickly enough to detect subsequent errors.
Add minimal overhead to the processing of correct programs.
11
13. Panic-Mode Recovery
Once an error is found, the parser intends to find designated
set of synchronizing tokens by discarding input symbols one
at a time.
Synchronizing tokens are delimiters, semicolon or } whose
role in source program is clear.
When parser finds an error in the statement, it ignores the rest
of the statement by not processing the input.
Advantage:
Simplicity
Never get into infinite loop
Disadvantage:
Additional errors cannot be checked as some of the input
symbols will be skipped.
13
14. Phrase-Level Recovery
When a parser finds an error, it tries to take corrective
measures so that the rest of inputs of statement allow the
parser to parse ahead. The corrections may be
Replacing a prefix by some string.
Replacing comma by semicolon.
Deleting extraneous semicolon.
Inserting missing semicolon.
Advantage:
It can correct any input string.
Disadvantage:
It is difficult to cope up with actual error if it has occurred before the
point of detection.
14
15. Error Productions
The use of the error production method can be incorporated if
the user is aware of common mistakes that are encountered in
grammar in conjunction with errors that produce erroneous
constructs.
Example: write 5x instead of 5*x
Advantage:
If this is used then, during parsing appropriate error messages can be
generated and parsing can be continued.
Disadvantage:
The disadvantage is that it’s difficult to maintain.
15
16. Global Correction
The parser considers the program in hand as a whole and tries
to figure out what the program is intended to do and tries to
find out a closest match for it, which is error-free.
When an erroneous input statement X is fed, it creates a parse
tree for some closest error-free statement Y.
Advantage:
This may allow the parser to make minimal changes in the source
code.
Disadvantage:
Due to the complexity (time and space) of this strategy, it has not
been implemented in practice yet.
16
19. Representative Grammars - CFG
Context-free grammars are named as such because any of the production
rules in the grammar can be applied regardless of context—it does not
depend on any other symbols that may or may not be around a given symbol
that is having a rule applied to it.
A context free grammar G is defined by four tuple format as
G = (V, T, P, S)
where,
G − Grammar
V − Set of variables
T − Set of terminals
P − Set of productions
S − Start symbol
19
20. Context Free Grammar
Terminals are symbols from which strings are formed.
Lowercase letters, i.e., a, b, c.
Operators, i.e., +,−, ∗.
Punctuation symbols, i.e., comma, parenthesis.
Digits, i.e., 0, 1, 2, · · · ,9.
Boldface letters, i.e., id, if.
Non-terminals are syntactic variables that denote a set of strings.
Uppercase letters, i.e., A, B, C.
Lowercase italic names, i.e., expr, stmt.
Start symbol is the head of the production stated first in the grammar.
Production is of the form LHS → RHS or head → body, where head
contains only one non-terminal and body contains a collection of
terminals and non-terminals.
20
21. Context Free Grammar
Example
E → E + T | E − T | T
T → T ∗ F | T / F | F
F → (E) | id
V = {E, T, F}
T = {+ , −, *, /, ( , ), id}
S = {E}
P :
E → E+T T→ T / F
E → E−T T→ F
E →T F→ (E)
T → T∗ F F→ id
21
23. Leftmost Derivation
At each and every step the leftmost non-terminal is expanded by substituting its
corresponding production to derive a string.
E → E + E | E ∗ E | id
23
24. Rightmost Derivation
At each and every step the rightmost non-terminal is expanded by substituting its
corresponding production to derive a string.
E → E + E | E ∗ E | id
24
26. Parse Tree
• Parse tree is a hierarchical structure
which represents the derivation of the
grammar to yield input strings.
• Root node of parse tree has the start
symbol of the given grammar from
where the derivation proceeds.
• Leaves of parse tree represent terminals.
• Each interior node represents
productions of grammar.
• If G : E → E+E | E*E | ( E ) | - E | id is
the grammar, then Parse tree for the
input string - (id + id) is shown.
26
28. References
Alfred V Aho, Jeffery D Ullman, Ravi Sethi, "Compilers, Principles
techniques and tools", Pearson Education 2011
https://www.gatevidyalay.com
https://electricalvoice.com
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