{"id":9706,"date":"2020-04-26T17:57:52","date_gmt":"2020-04-26T15:57:52","guid":{"rendered":"https:\/\/www.salvis.com\/blog\/?p=9706"},"modified":"2023-11-12T13:51:18","modified_gmt":"2023-11-12T12:51:18","slug":"syntax-highlighting-with-sql-developer","status":"publish","type":"post","link":"https:\/\/www.salvis.com\/blog\/2020\/04\/26\/syntax-highlighting-with-sql-developer\/","title":{"rendered":"Syntax Highlighting With SQL Developer"},"content":{"rendered":"\n

Introduction<\/h2>\n\n\n\n

A customer asked me if it is possible to show unused identifiers in SQL Developer. Since there is no PL\/SQL compile warning for that, you might be tempted to say no. But you can always use PL\/SQL Cop<\/a> for static code analysis. Guideline G-1030<\/a> deals with variables and constants and guideline G-7140<\/a> with procedures and functions. However, in this case, it’s also possible to achieve the same result by tweaking SQL Developer’s preferences for PL\/SQL Syntax Colors.<\/p>\n\n\n\n

In this blog post, I explain how custom syntax highlighting works in SQL Developer. I use a simple example first and then show how to highlight unused identifiers in SQL Developer.<\/p>\n\n\n\n

What Is Syntax Highlighting?<\/h2>\n\n\n\n

Wikipedia<\/a> defines syntax highlighting as follows<\/p>\n\n\n\n

\n

Syntax highlighting is a feature of text editors that are used for programming, scripting, or markup languages, such as HTML. The feature displays text<\/span>\n, especially source code, in different colors and fonts according to the category of terms.<\/span>\n(…)<\/p>\n<\/blockquote>\n\n\n\n

How Does Syntax Highlighting Work?<\/h2>\n\n\n\n

The next figure illustrates the highlighting process in SQL Developer. The similarities to the formatting process<\/a> are no accident.<\/p>\n\n\n\n

\"\"<\/a><\/figure>\n\n\n\n

I will explain each step and component in the next chapters.<\/p>\n\n\n\n

Please note that these are conceptual components, the actual implementation might look different.<\/p>\n\n\n\n

1. Parser<\/h3>\n\n\n\n

This step is identical to formatting process. The parser reads the unformatted plain SQL or PL\/SQL input and generates a parse-tree. The parse-tree is a hierarchical representation of the significant tokens of the input. In other words, there is neither whitespace nor comments in a parse-tree.<\/p>\n\n\n\n

Each node in the parse-tree includes the start and end position within the plain SQL input.<\/p>\n\n\n\n

2. Custom Styler<\/h3>\n\n\n\n

The custom styler needs the parse-tree and the Arbori program as input.<\/p>\n\n\n\n

Arbori is a query language for parse-trees. See my previous post<\/a> to learn more about it. The Arbori program is configured in the SQL Developer’s preferences under Code Editor<\/code> -> PL\/SQL Syntax Colors<\/code> -> PL\/SQL Custom Syntax Rules<\/code>.<\/p>\n\n\n\n

2.1. The Results<\/h4>\n\n\n\n

The custom styler basically only runs the Arbori program. It is responsible for producing two results:<\/p>\n\n\n\n

    \n
  1. All custom style names (dotted line to Styles)<\/strong>
    to be shown in the preferences under Code Editor<\/code> -> PL\/SQL Syntax Colors<\/code>. Allows the user to configure the foreground and background colours as well as the font style (normal, bold, italic). SQL Developer discovers styles during startup. For changes (new or renamed styles) to take effect you need to restart SQL Developer.<\/li>\n\n\n\n
  2. A list of node-style pairs (solid line to Node Style)<\/strong>
    to be rendered according to the configured style properties (foreground color, background color and font style).<\/li>\n<\/ol>\n\n\n\n

    2.2. The Default Arbori Program<\/h4>\n\n\n\n

    SQL Developer 19.4.0 provides the following default (I removed all multiline comments):<\/p>\n\n\n\n

    <\/circle><\/circle><\/circle><\/g><\/svg><\/span><\/path><\/path><\/svg><\/span>
    PlSqlColTabAlases<\/span>:                          -- <\/span><\/span>\n   [<\/span>node<\/span>) <\/span>c_alias<\/span>                           -- <\/span>Search<\/span> <\/span>all<\/span> <\/span>the<\/span> <\/span>nodes<\/span> <\/span>in<\/span> <\/span>the<\/span> <\/span>parse<\/span> <\/span>tree<\/span> <\/span>which<\/span> <\/span>are<\/span> <\/span>column<\/span> <\/span>aliases<\/span><\/span>\n | [<\/span>node<\/span>) <\/span>identifier<\/span>                        -- <\/span>Or<\/span> <\/span>nodes<\/span> <\/span>with<\/span> <\/span>identifier<\/span> <\/span>payload<\/span>,  <\/span><\/span>\n        & [<\/span>node<\/span>-<\/span>1<\/span>) <\/span>query_table_expression<\/span>   -- <\/span>which<\/span> <\/span>younger<\/span> <\/span>siblings<\/span> <\/span>are<\/span> <\/span>labeled<\/span> <\/span>with<\/span> <\/span>table<\/span> <\/span>names<\/span><\/span>\n->                                          -- <\/span>The<\/span> <\/span>semantic<\/span> <\/span>action<\/span> <\/span>symbol<\/span> (<\/span>to<\/span> <\/span>trigger<\/span> <\/span>syntax<\/span> <\/span>highlighting<\/span>).<\/span><\/span>\n;                                           -- <\/span>End<\/span> <\/span>of<\/span> <\/span>the<\/span> <\/span>rule<\/span><\/span>\n<\/span>\nPlSqlLogger<\/span>:<\/span><\/span>\n    [<\/span>pkg<\/span>) <\/span>name<\/span><\/span>\n  & (?<\/span>pkg<\/span> = <\/span>'DBMS_OUTPUT'<\/span> | ?<\/span>pkg<\/span> = <\/span>'APEX_DEBUG'<\/span> |<\/span><\/span>\n     ?<\/span>pkg<\/span> = <\/span>'LOG'<\/span>         | ?<\/span>pkg<\/span> = <\/span>'logger'<\/span>     -- <\/span>pattern<\/span> <\/span>match<\/span> <\/span>is<\/span> <\/span>case<\/span> <\/span>insensitive<\/span><\/span>\n  )   <\/span><\/span>\n  & (<\/span>pkg<\/span>^ = <\/span>node<\/span> | <\/span>pkg<\/span>^^ = <\/span>node<\/span>)<\/span><\/span>\n  & [<\/span>node<\/span>) <\/span>procedure_call<\/span><\/span>\n-><\/span><\/span>\n;<\/span><\/span><\/code><\/pre><\/div>\n\n\n\n
    The query names defined on line 1 (PlsqlColTabAlases<\/code>) and line 8 (PlSqlLogger<\/code>) define the style name used in the preference dialog under Code Editor<\/code> -> PL\/SQL Syntax Colors<\/code>.<\/p>\n\n\n\n
    2.3. Configuring Styles<\/h4>\n\n\n\n
    This screenshot shows how the PlSqlLogger<\/code> style is configured.<\/p>\n\n\n\n
    \"\"<\/a><\/figure>\n\n\n\n
    2.4 JavaScript Callback Functions<\/h4>\n\n\n\n
    The default Arbori program uses predefined Java callback functions in the CustomSyntaxStyle<\/code> class.<\/p>\n\n\n\n
    Since SQL Developer 19.2.0 you can use embedded JavaScript callback functions. As a result Java callback functions are not necessary anymore.<\/p>\n\n\n\n
    Here’s an example how to change PlSqlLogger<\/code> query to use a JavaScript callback function:<\/p>\n\n\n\n
    <\/circle><\/circle><\/circle><\/g><\/svg><\/span><\/path><\/path><\/svg><\/span>
    PlSqlLogger<\/span>:<\/span><\/span>\n    [<\/span>pkg<\/span>) <\/span>name<\/span><\/span>\n  & (?<\/span>pkg<\/span> = <\/span>'DBMS_OUTPUT'<\/span> | ?<\/span>pkg<\/span> = <\/span>'APEX_DEBUG'<\/span> |<\/span><\/span>\n     ?<\/span>pkg<\/span> = <\/span>'LOG'<\/span>         | ?<\/span>pkg<\/span> = <\/span>'logger'<\/span>     -- <\/span>pattern<\/span> <\/span>match<\/span> <\/span>is<\/span> <\/span>case<\/span> <\/span>insensitive<\/span><\/span>\n  )   <\/span><\/span>\n  & (<\/span>pkg<\/span>^ = <\/span>node<\/span> | <\/span>pkg<\/span>^^ = <\/span>node<\/span>)<\/span><\/span>\n  & [<\/span>node<\/span>) <\/span>procedure_call<\/span><\/span>\n-> {<\/span><\/span>\n  var <\/span>node<\/span> = <\/span>tuple<\/span>.<\/span>get<\/span>(<\/span>"node"<\/span>);<\/span><\/span>\n  struct.addStyle(<\/span>target<\/span>, <\/span>node<\/span>, <\/span>"PlSqlLogger"<\/span>);<\/span><\/span>\n}<\/span><\/span>\n;<\/span><\/span><\/code><\/pre><\/div>\n\n\n\n
    Important is line 10. It shows how to add a style for a node in the parse-tree.<\/p>\n\n\n\n
    2.5 JavaScript Global Variables<\/h4>\n\n\n\n
    The following variables are provided. You should know them when writing JavaScript callback functions.<\/p>\n\n\n\n