Chapter 3 - add vars and lexical scope. (#7)

* Chapter 3 - add vars and lexical scope.

* Fix typo

* Overhaul graph viz

Makes the scopes pointing into the graph being build more visually appealing.
Constants are a printed with just the constant value.

* Fix control edge color

* Fix missing grouping operator parse

Add a parens test.
Shorten names 'Identifier' to 'Id'
_lexer.match -> match
require() passes a Node thru, so can be flow-coded.
Uniform syntax error messages.
Handy Lexer.toString for debugging.
Drop Optional for null returns; less total code; less objects; less confusion.
camelCase some fcns.

* All parser helpers return Node, not void.

Drop _ret.  parseBlock and parseStatement now the same.

* CLosely align chap2 and chap3 parsers

Mostly whitespace aligned; dragged a few functions around to make more sense.
I think the diff from Ch2 and Ch3 is down a few differences about what is a statement, plus all the symbol stuff for scopes and variables.

* Add examples illustrating the symbol table creation.

* Update docs and comments

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Co-authored-by: Cliff Click <cliffc@acm.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/chapter02/docs/02-grammar.md b/chapter02/docs/02-grammar.md
index a4a79cea..1a1e1239 100644
--- a/chapter02/docs/02-grammar.md
+++ b/chapter02/docs/02-grammar.md
@@ -30,6 +30,7 @@ unaryExpression
 
 primaryExpression
     : INTEGER_LITERAL
+    | '(' expression ')'
     ;
 
 INTEGER_LITERAL