FIRST:
If α is any string of grammar symbols, the FIRST (α) be the set of terminals
that begins strings derived from α.
If αà€,
then € is also in FIRST (α).
To compute FIRST (α) for all grammar
symbols ’X’, apply the following rules until no more terminals or € can be
added to any FIRST set.
1) If
x is terminal ,the FIRST(x)={x}
2) If
x is non terminal and xà
aα...
Friday, October 4, 2013
There
are two parsing techniques, these parsing techniques work on the following
principle
1.
The parser scans the input string from left to right and identifiers that the
derivation is leftmost or rightmost.
2. The parser makes use of production
rules for choosing the appropriate derivation. The different parsing techniques
use different approaches in selecting the appropriate rules for derivation and
finally a parse tree is constructed.
When...
In this process of
compilation the parser and lexical analyzer work together. That means, when
parser required string of tokens it invokes lexical analyzer .In turn, the
lexical analyzer supplies tokens to syntax analyzer (parser).
The parser collects sufficient number of
tokens and builds a parse tree. Then by building the parse tree, parse smartly
finds the syntactical errors if any. It is also necessary that the parse should
recover...
The parser or syntax analysis checks
for whether the string given can be generated from the given grammar.
A parser for grammar G is a program that
takes as input a string w and produces as output either a parser tree for w, if
w is a sentences of G, or an end message indicating that w is not a sentence of
G. ...
Thursday, October 3, 2013
A.A.Puntambekar
Technical Publications, 01-Jan-2010 - Compilers (Computer programs) - 461 pages
Overview of Compilation : Phases of compilation - Lexical analysis, Regular grammar and regular expression for common programming language features, Pass and phases of translation, Interpretation, Bootstrapping, Data structures in compilation - LEX lexical analyzer generator.Top Down Parsing : Context free grammars, Top down parsing, Backtracking, LL (1), Recursive descent parsing, Predictive parsing, Preprocessing steps required for predictive parsing.Bottom...
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