LineAppendable

LineAppendableImpl is a replacement for LineFormattingAppendable intended to facilitate creating line based, formatted output including keeping track of source offset information by using SegmentedBuilder for accumulating the output to SegmentedSequence final result.

⚠️ Work in Progress

Format

Formatting features include removing/adding prefix to each line as it is generated, collapsing spans of spaces to a single space, removing leading and/or trailing spaces of each line.

The implementation accumulates output as a list of lines. For each line the appendable keeps position for each line where its prefix end and line text begins.

On appending of an EOL the accumulated line is committed and added to the list of accumulated lines.

Line which is in the process of being accumulated is accumulated in its own SegmentBuilder to allow quick modification or regeneration of the line's text with minimal performance penalty.

Options

Options define the behaviour of the appendable during output construction:

• CONVERT_TABS: expand tabs on column multiples of 4
• COLLAPSE_WHITESPACE: collapse multiple tabs and spaces to single space
• SUPPRESS_TRAILING_WHITESPACE: don't output trailing whitespace
• PASS_THROUGH: just pass everything through to appendable with no formatting
• ALLOW_LEADING_WHITESPACE: allow leading spaces on a line, else remove
• ALLOW_LEADING_EOL: allow EOL at offset 0
• PREFIX_PRE_FORMATTED: when prefixing lines, prefix pre-formatted lines

ℹ️ COLLAPSE_WHITESPACE overrides CONVERT_TABS because converted tags will be converted to a space.

Formatting Features

LineAppendable tracks the length and column of the accumulating line to facilitate formatting decisions by rendering code.

LineAppendable provides methods to allow applying conditional formatting logic based on accumulated output generated by child elements of a given node, specifically applying prefix change only after an EOL is appended or registering callbacks when an EOL is appended.

It is also possible to modify the prefixes for lines, after they are constructed. However, the core renderers perform their activity without resorting to modifying the lines after they are committed.

Line prefix modification feature is used by Markdown Navigator plugin when accumulating text from JetBrains IDE parse tree which is not ideally suited for tracking parent prefixes.

For this purpose the LineAppendable allows modifying the prefix end of each line as parent prefixes are removed from the text.