Recursive descent parser: Difference between revisions

Revision as of 22:55, 29 March 2006

Revision as of 08:02, 31 March 2006

Line 15:

[[Algorithms + Data Structures = Programs]]) is in [[LL parser|LL(1)]] form:

program = block "." .

<pre>

program = block "." .

block =

["const" ident "=" number {"," ident "=" number} ";"]

block =

[ "constvar" ident "=" number {"," ident "=" number} ";"]

[ {"varprocedure" ident {",;" ident}block ";"]} statement .

{ "procedure" ident ";" block ";" } statement .

statement =

factor = [ident | number | "(:=" expression ")" .

statement =

[ ident| ":=call" expressionident

| "whilebegin" conditionstatement {"do;" statement} "end"

| "call" ident

| "beginif" statementcondition {";then" statement } "end"

| "ifwhile" condition "thendo" statement

] .

| "while" condition "do" statement

].

condition =

"odd" expression

condition =

| expression ("odd="|"#"|"<"|"<="|">"|">=") expression

.

| expression ("="|"#"|"<"|"<="|">"|">=") expression

.

expression = [ "+"|"-"] term { ("+"|"-") term} .

expression = [ "+"|"-"] term { ("+"|"-") term} .

term = factor {("*"|"/") factor} .

term = factor {("*"|"/") factor} .

factor = ident | number | "(" expression ")" .

factor = ident | number | "(" expression ")" .

</pre>

[[Terminal symbol|Terminals]] are expressed in quotes (except for the well defined ''ident''