This module provides tools for building a tree from a string or a list of blocks. As noted in the README, a tree is represented in text as an outline:
> data = "1\n 2\n 3\n 4\n5\n 6\n 7"To build a tree from it, we apply the function fromString:
fromString :
node
-> (Block -> a)
-> String
-> Result Error (Tree a)
> fromString "?" .content data
Tree "0" [
Tree "1" [Tree "2" [],Tree "3" [], Tree "4" []]
, Tree "5" [Tree "6" [],Tree "7" []]
]The first argument of fromString is a label for a default node. The second argument tells how to build a node from a Block. In the example, we are building a tree with string labels, so we need a function of type (Block -> String). Recall that
type alias Block = { indent : Int, content: String }Therefore
.content : Block -> Stringhas the correct type. Here we use the representation of rose trees found in elm/rose-tree.
Note. The build functions described here here make a guess as to what the "quantum of indentation" is. The quantum of indentation is the largest integer Q such that all lines are indented by some multiple of Q. The guess used is either 1 or the number of leading spaces in the first line that has leading spaces.
Example:
> Build.forestFromString
"?"
.content
(\str -> {indent = 0, content = str})
"1\n 2\n 3\na\n b\n c"
Ok [ Tree "1" [Tree "2" [],Tree "3" []]
,Tree "a" [Tree "b" [],Tree "c" []]
]