Article Categories
- All Categories
-
Data Structure
-
Networking
-
RDBMS
-
Operating System
-
Java
-
MS Excel
-
iOS
-
HTML
-
CSS
-
Android
-
Python
-
C Programming
-
C++
-
C#
-
MongoDB
-
MySQL
-
Javascript
-
PHP
-
Economics & Finance
Articles on Trending Technologies
Technical articles with clear explanations and examples
What is Intermediate Code Generation?
Intermediate code can translate the source program into the machine program. Intermediate code is generated because the compiler can’t generate machine code directly in one pass. Therefore, first, it converts the source program into intermediate code, which performs efficient generation of machine code further. The intermediate code can be represented in the form of postfix notation, syntax tree, directed acyclic graph, three address codes, Quadruples, and triples.If it can divide the compiler stages into two parts, i.e., Front end & Back end, then this phase comes in between.Example of Intermediate Code Generation −Three Address Code− These are statements of form ...
Read MoreWhat is Implementation of Syntax Directed Translators?
A syntax-directed translation scheme is a context-free grammar in which attributes are related to the grammar symbol and semantic actions enclosed within braces ({ }). These semantic actions are the subroutines that are known by the parser at the suitable time for translation. The location of the semantic actions on the right side of production denotes the time when it will be known for implementation by the parser.When it can produce a translation scheme, it should provide that an attribute value is available when the action defines it. This needed thatInherited attributes of a symbol on the right side of ...
Read MoreWhat is Types of Syntax Directed Translation Schemes?
There are two types of Syntax directed translation schemes which are as follows −Synthesized TranslationIn this translation, values of variables on L.H.S of a production rule depend on the value of the variable on R.H.S of production rule.For Example, E → E(1) + E(2) {E. VAL = E(1). VAL + E(2). VAL}Here, E on L.H.S of production rule can be computed by the sum of values of E(1) and E(2) which are on R.H.S of a production rule, i.e., L.H.S variable is dependent on R.H.S variables.In synthesized translation, the value of the synthesized attribute at the node is evaluated ...
Read MoreWhat is the Syntax Directed Translation?
In syntax directed translation, along with the grammar it can identify some informal notations and these notations are known as as semantic rules.After implementing the Semantic Analysis, the source program is modified to an intermediate form.There is some information that is required by the Intermediate code generation phase to convert the semantically checked parse tree into intermediate code. But this information or attributes of variables cannot be represented alone by Context- Free Grammar.So, some semantic actions have to be attached with Context-Free grammar which helps the intermediate code generation phase to generate intermediate code.So, Attaching attributes to the variables of ...
Read MoreFind FIRST & FOLLOW for the following GrammarnE → E + T|TnT → T ∗ F|FnF → (E)|id
SolutionComputation of FIRSTE → E + T|TSince FIRST (E) does not contain ε.∴ FIRST (E) = FIRST(E + T) = FIRST(E)As, E → T∴ FIRST (E) = {FIRST(T)} (1)T → T ∗ F|FAs FIRST (T) does not contain ε or T does not derive ε.∴ FIRST (T) = FIRST(T ∗ F) = {FIRST(T)}As, T → F (FIRST(T) = {FIRST(F)} (2)F → (E)|id∴ By Rule (3)of FIRSTFIRST (F) = {(, id} ...
Read MoreFind the missing numbers in a sequence in R data frame column.
To find the missing numbers in a sequence in R data frame column, we can use setdiff function.For Example, if we have a data frame called df that contains a column say X and we want to check which values between 1 to 20 are missing in this column then we can use the below command −setdiff(1:20,df$X)Example 1Following snippet creates a sample data frame −x
Read MoreHow to extract columns having at least one non-duplicate in R?
To extract columns from an R data frame having at least one non-duplicate, we can use Filter function.For Example, if we have a data frame called df that contains some columns having duplicate values and columns that do not contains at least one non-duplicate then we can extract columns having at least one non-duplicate by using the below command −Filter(var,df)Example 1Following snippet creates a sample data frame −x1
Read MoreCreate bar plot for grouped data of two columns in base R.
To create bar plot for grouped data in base R, we can create the table for both the columns and then use beside argument of barplot function to create the bar plot. To differentiate between the bars, we need to set legend argument to TRUE as well. To understand how it can be done check out the below Example.ExampleFollowing snippet creates a sample data frame −G
Read MoreGet a matrix as Output if a condition for a single value is met in R.
If we want to check a condition and the Output based on that condition needs to be a matrix then we can use if else function in R.For Example, if we have a value say V = 5 and we want to get matrix M1 if V is equal to 5 and matrix M2 if V is not equal to 5 then we can use the below command −if (V == 5) M1 else M2ExampleFollowing snippet creates a sample matrices −M1
Read MoreWhat is Implementation of LR Parsing Tables?
LR Parsing Tables are a two-dimensional array in which each entry represents an Action or goto entry. A programming language grammar having a large number of productions has a large number of states or items, i.e., I0, I1 … … In.So, due to more states, more Actions & goto entries will be filled, which requires a lot of memory. So, a two-dimensional array is not sufficient to store so many action entries, because each entry requires at least 8 bits to encode.So, we have to use more efficient encoding than a two-dimensional array for encoding, Action & goto field.For example, ...
Read More