Target Language Compiler

Interpreting Records

Here is the output from a TLC program script that reads guide.rtw, interprets its records, manipulates field data, and formats descriptions, which are directed to the MATLAB command window:

• Using TLC you can:
  * Directly access any field's value, e.g.
    %<Top.Date> -- evaluates to:
    "21-Aug-2008"
    
  * Assign contents of a field to a variable, e.g.
    "%assign worker = Top.Employee.FirstName"
    worker <- Top.Employee.FirstName = Arthur
  
  * Concatenate string values, e.g.
    "%assign worker = worker + " " + Top.Employee.LastName"
    worker <- worker + " " + Top.Employee.LastName = "Arthur Dent"
    
  * Perform arithmetic operations, e.g.
    "%assign wageCost = Top.Employee.PayRate * Top.Employee.Overhead"
    wageCost <- Top.Employee.PayRate * Top.Employee.Overhead <- 11.5 * 1.78 = 20.47
    
  * Put variables into a field, e.g.
    "%assign Top.Employee.GrossRate = wageCost"
    Top.Employee.GrossRate <- wageCost = 20.47
    
  * Traverse lists of values, e.g.
    "%assign projects = Top.Project[0].Name + ", " + Top.Project[1].Name..."
    "+ ", " + Top.Project[2].Name"
    projects <- Top.Project[0].Name + ", " + Top.Project[1].Name
    + ", " + Top.Project[2].Name = Tea, Gillian, Zaphod
  
  * Traverse and manipulate list data via loops, e.g.
    - At top of Loop, Project = Tea; Difficulty = 3
    - Bottom of Loop, i = 0; diffSum = 3.0
    - At top of Loop, Project = Gillian; Difficulty = 8
    - Bottom of Loop, i = 1; diffSum = 11.0
    - At top of Loop, Project = Zaphod; Difficulty = 10
    - Bottom of Loop, i = 2; diffSum = 21.0
  Average Project Difficulty = DiffSum / Top.NumProjects = 21.0 / 3 = 7.0
  

This "presentation" of guide.rtw was produced by invoking the Target Language Compiler from the MATLAB command window, executing a script called read-guide.tlc. Do this yourself now, by following these steps:

1. If you haven't already done so, copy the directory tlctutorial/guide to your working directory.
2. In MATLAB, cd to /guide within your working directory
3. To produce the output just listed, process guide.rtw with the TLC script read-guide.tlc by typing the following command:

• tlc -v -r guide.rtw read-guide.tlc
  

Note command usage:

• The input data file (guide.rtw) is signalled by the -r switch.
• The TLC script handling the data file is specified by the last token typed.
• The -v switch (for verbose) is needed to direct output to the command window, unless the TLC file handles this itself.

Structure of Record Files

Anatomy of a TLC Script