diff options
Diffstat (limited to 'Parser/pgen/pgen.py')
| -rw-r--r-- | Parser/pgen/pgen.py | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/Parser/pgen/pgen.py b/Parser/pgen/pgen.py index d7dcb76..2f444eb 100644 --- a/Parser/pgen/pgen.py +++ b/Parser/pgen/pgen.py @@ -10,11 +10,11 @@ Concepts * An LL(1) parser (Left-to-right, Leftmost derivation, 1 token-lookahead) is a top-down parser for a subset of context-free languages. It parses the input from Left to right, performing Leftmost derivation of the sentence, and can - only use 1 tokens of lookahead when parsing a sentence. + only use 1 token of lookahead when parsing a sentence. * A parsing table is a collection of data that a generic implementation of the LL(1) parser consumes to know how to parse a given context-free grammar. In - this case the collection of thata involves Deterministic Finite Automatons, + this case the collection of data involves Deterministic Finite Automatons, calculated first sets, keywords and transition labels. * A grammar is defined by production rules (or just 'productions') that specify @@ -26,9 +26,9 @@ Concepts rule_name: rule_description; - meaning the rule 'a: b' specifies that a can be replaced by b. A Context-free - grammars is a grammars in which the left-hand side of each production rule - consists of only a single nonterminal symbol. Context free grammars can + meaning the rule 'a: b' specifies that a can be replaced by b. A context-free + grammar is a grammar in which the left-hand side of each production rule + consists of only a single nonterminal symbol. Context-free grammars can always be recognized by a Non-Deterministic Automatons. * Terminal symbols are literal symbols which may appear in the outputs of the @@ -47,8 +47,8 @@ Concepts * The first sets of a rule (FIRST(rule)) are defined to be the set of terminals that can appear in the first position of any string derived from the rule. - This is useful for LL(1) parsers as the parser is only allow to look at the - next token in the input to know which rule needs to parse. For example given + This is useful for LL(1) parsers as the parser is only allowed to look at the + next token in the input to know which rule needs to parse. For example, given this grammar: start: '(' A | B ')' |