Editing LL parser (section)

=== Set up ===
To explain an LL(1) parser's workings we will consider the following small LL(1) grammar:
# S → F
# S → '''(''' S '''+''' F ''')'''
# F → '''a'''
and parse the following input:
: '''(''' '''a''' '''+''' '''a''' ''')'''

An LL(1) parsing table for a grammar has a row for each of the non-terminals and a column for each terminal (including the special terminal, represented here as '''$''', that is used to indicate the end of the input stream).

Each cell of the table may point to at most one rule of the grammar (identified by its number). For example, in the parsing table for the above grammar, the cell for the non-terminal 'S' and terminal '<nowiki/>'''('''<nowiki/>' points to the rule number 2:

: {| class="wikitable"
!
! (
! )
! a 
! +
! $
|- align="center"
! S
|   2       || {{sdash}} ||  1         ||  {{sdash}}     
| {{sdash}}
|- align="center"
! F
| {{sdash}} || {{sdash}} ||  3         ||  {{sdash}}    
| {{sdash}}
|}

The algorithm to construct a parsing table is described in a later section, but first let's see how the parser uses the parsing table to process its input.