Make Timesheet Parser with Hoa Compiler

I have been keeping my timelogs in a plain-text timesheet format as follows:

2019-02-11
09:00 [JIRA-1234] Adding some functionality
10:00 [standup]
10:15 [JIRA-1234] Fixing that annoying bug
11:00 [JIRA-2134] Review
12:00 [lunch]
13:00 [JIRA-1234] @pairing
14:00 [confused]
18:00 [finish]

2019-02-12
09:00 ...

Bascially, it’s much quick to log my time realistically. I don’t need to continually break my concentration and assign time to tickets as I work on them, or strain to remember (or make up) what I did at the end of the day, or even at the end of the week. It also means I can record what really happened, and not just logging random events on the ZZ-22 “catch-all” ticket where the information is lost to the powers of analysis.

The only problem is that every week I need to translate this into not one but two JIRAs, this is an operation that involves a huge amount of clicking and waiting and confusion and ppaaiinn.

So, pain once a week instead of pain every day. But there is no reason that this situation cannot be ameliorated - we can parse the timesheet. Once we parse the timesheet we can sync it automatically with JIRA and my Monday morning trauma is at an end, and our project managers can be happier as I can accurately curate and log my time every day effortlessly.

And, the miscellaneous tickets can still be assigned to a bucket ticket, but at least the original information is preserved,

Parsing the Timesheet

Why do we want to parse the timesheet? We want to extract the information from it, and eventually produce a data structure like:

[
    '2019-01-01' => [
        'entries' => [
            [ 'time' => '10:00', 'category' => 'AN-1234', 'comment' => 'foobar' ],
            [ 'time' => '11:00', 'category' => 'lunch', 'comment' => 'foobar' ],
        ]
    ],
    '2019-01-02' => [
        'entries' => [
            [ 'time' => '10:00', 'category' => 'AN-456', 'comment' => 'foobar' ],
        ]
    ]
]

Once we have structured data we can do something useful with it.

We could use regular expressions to extract the data, but, well, it might not end well. Instead we are going to use a compiler and we are not going to write any PHP code at all.

The HOA Compiler

The HOA Compiler. The HOA Compiler is an amazing library which can take a grammar in the form of a .pp file (see here for good and detailed documentation).

The timesheet document is composed of one or more date entries (of the form YYYY-MM-DD) and each date entry consequently contains a list of entry items, each defining the time, and optionally a category, comment and one or more tags.

Let’s skip straight to it:

%token newline            \n
%token space              \s
%token date               [0-9]{4}-[0-1][0-9]-[0-3][0-9] -> entry

%token entry:time         [0-9]{1,2}:[0-9]{1,2}
%token entry:break        \n\n -> default
%token entry:newline      \n
%token entry:space        \s
%token entry:text         [a-zA-Z0-9'"\h.-]+
%token entry:tag          @[a-zA-Z0-9-_]+
%token entry:bracket_     \[ -> category

%token category:name      [A-Za-z-_0-9]+
%token category:_bracket  \] -> entry

#document:
    date()*

#date:
    <date> <newline>? entry()*

#entry:
    <time> <space>? category()? <space>? <text>? tag()* (<newline> | <break> )?

#category:
    <bracket_> <name> <_bracket>

#tag:
    <space>? <tag>

So first we have the tokens, which are PCRE (regex) patterns. These define lexemes the which are like the “atoms” of our grammar. We then define the rules which combine these atoms - when prefixed with # become nodes in the AST (more on this later). Note the following:

  • The document has zero or many (*) date() rules.
  • Each date() rule is composed of a <date> followed by zero or one (?) newlines, followed by one or many entry() rules.
  • Each entry() rule must have a valid <time> token, followed by one or zero spaces, followed by a category() rule, followed by… etc.

Did you notice the -> symbols? These are namespace transitions, they mean that, when encountring a date token the lexer should switch to the date namespace - and it will then only consider tokens in this namespace, this is necessary to stop rules conflicting (you don’t want to interpret a date token in a category for example). The Compiler also allows you to transition to the previous namespace using __shift__ (see the docs for more info).

When there is no namespace, the default namespace is implicitly used. When there is a break token in the date namespace (two new lines as defined above) we revert back to the default namespace and can consider f.e. the date token again.

Namespaces are essential, and are what really help make the compiler a much better option than simple regular expressions.

You may notice that we parse the category as a rule, and the tag as a token. There is no particular reason for this other than laziness - we could also have parsed the category as a token, or the tag as a rule, but let’s look at the difference when the AST is rendered:

Tag:

#tag
>  token(entry:space,  )
>  token(entry:tag, @barfoo)

Category:

#category
>  token(entry:bracket_, [)
>  token(category:name, AA-1234)
>  token(category:_bracket, ])

The information we really want from the above two examples is the name - barfoo and AA-1234 respectively. With the category we can easily extract this information from the token in the AST, but with the tag we need to perform additional processing (e.g. ltrim('@barfoo', '@')) in order to obtain the tag name (barfoo), with the category it is less trivial.

But wait, how did we get here?

Parsing the Timesheet

In order to do anything useful, we want to get our hands on an AST (Abstract Syntax Tree). This will be the data structure containing all of our data, more-or-less neatly organized into a tree structure of nodes (remember these are defined in the grammar with the # prefix, e.g. #entry), each node contains the set of tokens (and their values) defined in the rule.

We use the HOA Compiler as follows:

use Hoa\Compiler\Llk\Llk;
use Hoa\File\Read;

$compiler = Llk::load(new Read(__DIR__ . '/../../resources/timesheet.pp'));
$ast = $compiler->parse($string);
// profit!

Once we have the AST we can visualize it using the Dumper class provided by HOA:

use Hoa\Compiler\Visitor\Dump;

$dumper = new Dump();
echo $dumper->visit($ast);

Producing something like this:

>  #document                             
>  >  #date                                 
>  >  >  token(date, 2019-01-01)                       
>  >  >  token(entry:newline,             
)                                           
>  >  >  #entry                                                                                                                       
>  >  >  >  token(entry:time, 10:00)   
>  >  >  >  token(entry:space,  )           
>  >  >  >  token(entry:text, Fo)                                                                                                     
>  >  >  >  token(entry:newline,                     

Walking the AST

The AST variable has type TreeNode and can be traversed easily with helper methods such as getChildren(), to do something useful with it, you will probably want to walk the tree, the basic idea is something like the following:


class TreeWalker
{
    public function walk(TreeNode $node): array
    {
        $dates = [];
        foreach ($node->getChildren() as $childNode) {
           if ($childNode->getId() === 'date') {
               $dates[] = $this->walkDate($childNode);
           }
        }

        return $dates;
    }

    private function walkDate(TreeNode $node): array
    {
        $date = [
            'entries' => [],
        ];

        foreach ($node->getChildren() as $childNode) {
            if ($childNode->getValueToken() === 'date') {
                $date['date'] = new DateTimeImmutable($childNode->getValueValue()));
            }

            if ($childNode->getId() == 'entry') {
                $date['entries'][] = $this->walkEntry($childNode));
            }
        }

        return $date;
    }

    private function walkEntry(TreeNode $node): array
    {
        // etc.
    }
}

The result would be something like:

[
    'date' => '2019-21-13',
    'entries' => [
        [
            // ...
        ],
        [
            // ...
        ]
    ],
    'date' => '2019-21-14',
    'entries' => [
        [
            // ...
        ],
        [
            // ...
        ]
    ],
]

This is a simplified version, see here for the complete version.

Note that we progressively build our data set and extract information from the tokens in the tree.

Summary

Now that we have walked the AST we have a data structure suited to our needs, and the next step is to build some rudimentary reporting and then integrate with the JIRA API. Along the way the above will probably change significantly - but fortunately it is now easy to change.

The official documentation provides a much greater depth of knowledge than this blog post does, but it is perhaps useful to see it explained from a different perspective.

Here is to great and future hopes of increased productivity powered by HOA.