dschwen/JSHit

Javascript library for parsing, modifying, and printing HIT files.

JSHit

JSHit is a Javascript librarty to build, parse, modify, and serialize HIT syntax trees. HIT is the input file format for the MOOSE framework.

Reference

HITNode

HITNode represents a block (or the top level of the input), that can have subblocks (which are also HITNode objects) and parameter/value pairs. For parameters a HITNode behaves like a Javascript Object and values can be accessed using the [] operator.

constructor(name)

var diffusion = new HITNode('diffusion'); constructes a new block with the name diffusion. The name is optional and is only required if the constructed block is inserted in a tree.

var root = new HITNode(); constructs an unnamed note that could serve as the root for a new tree.

block(path)

The block function will return a reference to any subblock of the current node, that is indexed by the given path. The block method will insert all required levels of subblocks and will always return a valid HITNode reference.

index()

The index method will build an internal index of all {{...}} placeholder values. Any tree must be indexed prior to calling the set method.

set(key, value)

set will replace all occurences of the {{key}} placeholder with value. set can be called repeatedly for each key as the locations of the placeholders are stored when indexing the tree using the index method.

print()

A tree can be serialized into a HIT string using the print method.

insert(node)

A seperately constructed node or subtree can be inserted as a child to the current node using the insert method.

const HITNode = require("./hit_node");

var root = new HITNode();
var kernels = root.block("Kernels");

diffusion = new HITNode('diffusion')
diffusion.type = 'Diffusion';
diffusion.variable = 'u';

kernels.insert(diffusion);
console.log(root.print());

will print

[Kernels]
  [diffusion]
    type = Diffusion
    variable = u
  []
[]

merge(node)

merge will combine the contents of node into the current node adding parameters and subblocks of node as parameters and subblocks of the current node.

Examples

Building and serializing a HIT tree

const HITNode = require("./hit_node");

root = new HITNode();
all = root.block("Modules/TensorMechanics/Master/all");
all['stress'] = 'FINTE';

console.log(root.print());

will print

[Modules]
  [TensorMechanics]
    [Master]
      [all]
        stress = FINTE
      []
    []
  []
[]

Parsing an input file

Given an input file text input_text a modifiable HIT tree can be build using HITParse

const HITParse = require("./hit_parser");

HITParse("[Executioner]\ntype=Steady\n[Timestepper]type=IterationDT\ndt=1.0\nfactor={{my_factor}}\n[]\n[]").then(root => {
  console.log(root.print());
});

will print

[Executioner]
  type = Steady
  [Timestepper]
    type = IterationDT
    dt = 1.0
    factor = {{my_factor}}
  []
[]

Substituting {{placeholder}} values

const HITParse = require("./hit_parser");

HITParse("[Executioner]\ntype=Steady\n[Timestepper]type=IterationDT\ndt=1.0\nfactor={{my_factor}}\n[]\n[]").then(root => {
  root.set('my_factor', 123.0);
  console.log(root.print());
});

will print

[Executioner]
  type = Steady
  [Timestepper]
    type = IterationDT
    dt = 1.0
    factor = 123
  []
[]