add draft for forge article

contents/writing/about/forge-configuration-parser/index.md

@@ -0,0 +1,76 @@
+---
+title: Forge configuration parser
+author: Brett Langdon
+date: 2015-06-19
+template: article.jade
+---
+
+
+---
+
+## TODO: Fix this starting paragraph
+Ok, job is great, lets talk about code! I have always had the aspiration of writing my own
+programming language. It is something I never went through as part of my "higher"
+education and it has always greatly interested me. I have always made attempts here and
+there to learn what I can about how they work and try to deconstruct existing languages or
+build what I can of new ones. I have never been very successful, but I am always learning.
+
+I finally feel that I am making a bit of progress in my learning. Recently I was working
+on a project in [go](http://golang.org/) and where I started was trying to determine what
+configuration language I wanted to use and whether I tested out
+[YAML](https://en.wikipedia.org/wiki/YAML) or [JSON](https://en.wikipedia.org/wiki/JSON)
+or [ini](https://en.wikipedia.org/wiki/INI_file), nothing really felt right. What I really
+wanted was a format similar to [nginx]() but I couldn't find any existing packages for go
+which supported this syntax. A-ha, I smell an opportunity. The project I started is
+[forge](https://github.com/brettlangdon/forge). Currently it is still nothing too
+impressive, but I feel like it marks a step in my quest for creating a programming
+language.
+
+**Example config file:**
+```cfg
+# Top comment
+global = "value";
+section {
+  a_float = 50.67;
+  sub_section {
+    a_null = null;
+    a_bool = true;
+    a_reference = section.a_float;  # Gets replaced with `50.67`
+  }
+}
+```
+
+Effectively what I wrote was a programming language. A very very simple one, but one none
+the less a programming language. Basically what this library does is take a configuration
+file in the specific format and parses it into an intermediate format. In this case it
+ends up being a `map[string]interface{}` but if it were a programming language it could
+end up being an [Abstract Syntax Tree](https://en.wikipedia.org/wiki/Abstract_syntax_tree)
+(AST) which is the intermediate representation that some languages use before compiling
+the source into machine code or [bytecode](https://en.wikipedia.org/wiki/Bytecode).
+
+The code itself is comprised of two main parts, the tokenizer (or scanner) and the
+parser. The tokenizer turns the raw source code (like above) into a stream of tokens. If
+you printed the token representation of the code above, it could look like:
+
+```
+(COMMENT, "Top comment")
+(IDENTIFIER, "global")
+(EQUAL, "=")
+(STRING, "value")
+(SEMICOLON, ";"
+(IDENTIFIER, "section")
+(LBRACKET, "{")
+(IDENTIFIER, "a_float")
+(EQUAL, "=")
+(FLOAT, "50.67")
+(SEMICOLON, ";")
+....
+```
+
+Then the parser takes in this stream of tokens and tries to parse them based on some known
+grammar. For example, a directive is in the form `<IDENTIFIER> <EQUAL> <VALUE>
+<SEMICOLON>` (where `<VALUE>` can be `<STRING>`, `<BOOL>`, `<INTEGER>`, `<FLOAT>`,
+`<NULL>`, `<REFERENCE>`). When the parser sees `<IDENTIFIER>` it'll look ahead to the next
+token to try and match it to this rule, if it matches then it knows to add this setting to
+the internal `map[string]interface{}` for that identifier. If it doesn't match anything
+then it has a syntax error and will throw an exception.