The source files gpc-lex.c
and pascal-lex.c
contain
the so-called lexical analyzer of the GNU Pascal compiler.
The latter file was created using flex
from
pascal-lex.l
. This very first stage of the compiler (after
the preprocessor which is a separate executable) is responsible for
reading what you have written and dividing it into tokens,
the “atoms” of each computer language. The main entry point is the
function, yylex
which calls the flex-generated function
lexscan
which does the main work of token separation.
Here is, for example, where the real number 3.14
and the
subrange of integers 3..14
are distinguished, and where
strings constants, symbols etc. are recognized.