^^Parsing (a string of a language).

≡ parsing  ≡  syntax analysis  ≡  syntactic analysis  ≡  analisi sintattica

≡ construction history ≡ derivation history

parsing an arithmetic expression;  arithmetic expression parser
e' il caso piu' semplice, archetipico di parsing

es:  2+3*4  deve essere calcolata come 2+(3*4) e non  (2+3)*4

to transform a string of symbols into a structure (usually parse tree),
according to rules.
An essential operation for working with a language.
Recognizing is one of its functions.
Etimo da "pars orationis" (parte del discorso, part of speech)
chi opera il parsing, uomo o programma.
Di solito i parser non sono scritti a mano, ma bensi' da generatori di parser.

Oss: i "trees" generati dai parser sono "trees-data_structures", legati ma non uguali ai "trees" della matematica, disambigua

Parsing is important because

a derivation usually brings out the "meaning" of the string.

Es. for a computer program, a derivation of the program in the program grammar tells the compiler how the program should be executed.


  1. parsing a string of a language
  2. parsing a string
  3. parsing a language; to parse a language
  4. parsing a natural language, parsing a  formal language.
  5. Nel caso di linguaggio naturale: parsing di uno scritto o di un parlato.
  6. "parsing" e'  comune a linguistica e informatica, with slightly different meanings.

vo: parsing  VS  parser

Come dire "tornire VS tornio-tornitore".

Azione e cosa.

10 parti del discorso della grammatica italiana

nome aggettivo articolo pronome numerale verbo avverbio preposizione congiunzione interiezione

"Parsing" da "pars orationis" (parte del discorso, part of speech)

Altera pars orationis non oratoris ingenium sed consulis auxilium implorat et flagitat



recognizer    lexical analysis  Parsing timeline#recognizer ;   wp

recognize whether an arbitrary string belongs to its language or not.
It's one of the functions of a parser.

To describe recognizers, formal language theory uses separate formalisms, known as automata theory.

One of the interesting results of automata theory is that

it is not possible to design a recognizer for certain formal languages.


lexical analysis  ≡  lexing  ≡  tokenization  
made by   lexer  ≡  tokenizer

in computer science is the process of converting

A lexer is generally combined with a parser, which together analyze the syntax of the string. 


Links librosito

  1. Parsing timeline. | parser_(Parsing timeline)
  2. Python BNF.
  3. Linguistica. Poiche' "parsing" e' tema comune a linguistica e programmazione.
  4. vo: Sintassi. | Linguaggio: grammatica, semantica, sintassi.

Links wp

  1. wp/Parsing | wp/Parse_tree | wp/Abstract_syntax_tree
  2. wp/Lexer, Lexical_analysis
  3. wp/Garden-path_sentence  "The old man the boat."
  4. wp/Part_of_speech | wp/Parti_del_discorso della grammatica classica.
  5. Compiler


  1. https://www.engr.mun.ca/~theo/Misc/exp_parsing.htm 
    Parsing Expressions by Recursive Descent
    Theodore Norvell (C) 1999 with updates later on.