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/** Count the indent level and return where the indent level stops in "i"

* A tab is counted as one indent.

* Params:

* i = the index to start looking from. This is mutated

* by reference to indicate the index the last index

* was.

* spaces_per_indent = the number of spaces to treat as one indent

int count_indents(ref int i, string input, int spaces_per_indent=4) {

int nspaces = 0;

if (i == input.length || !(input[i] == ' ' || input[i] == '\t')) {

return 0;

}

for (; i < input.length; ++i) {

switch (input[i]) {

case ' ': nspaces++; break;

case '*': nspaces++; break;

case '\t': nspaces += spaces_per_indent; break;

// Commented out makes it only accept "-"

//case '-': return nspaces / spaces_per_indent;

case '\n': nspaces = 0; break;

//default : return 0;

default : return nspaces / spaces_per_indent;

}

return nspaces / spaces_per_indent;

}

unittest {

int i;

assert(count_indents(i = 0, " - hi") == 1);

assert(count_indents(i = 0, "Foo") == 0);

assert(count_indents(i = 0, " - hi") == 2);

assert(count_indents(i = 0, "\t - hey") == 1);

}

void doNothing(T)(T _=null) {}

/** A streaming parser for Markdown trees. Emits a stream of parsing events.

* Params:

* ParseEventHandler = struct that handles a stream of parsing events.

* See [ExampleParseEventHandler] for an example.

* deleStart = function that is called with the return value of

* the ParseEventHandler's start(). Defaults to

* doNothing

* deleEnd = function that is called with the return value of

* the ParseEventHandler's end(). Defaults to

* doNothing

* These are all compile-time (template) parameters, thus the compiler will

* inline functions into generated code.

void parse(ParseEventHandler,

alias deleStart=doNothing,

alias deleEnd=doNothing,

bool relaxed=false,

Args...)

(string input, int spaces_per_indent, string title, Args args) {

import std.traits;

ParseEventHandler handler = ParseEventHandler(args);

//const initial_indent_level =

int current_indent_level;

//BitType current_bits;

//BitType[] stack;

int line_content_start_index;

int line_start_index;

// Workwround for void not being a parameter type

void emitBlockStart(string nodeContent) {

static if (is(ReturnType!(handler.start) == void)) {

handler.start(nodeContent);

deleStart();

} else deleStart(handler.start(nodeContent));

}

void emitBlockEnd() {

static if (is(ReturnType!(handler.end) == void)) {

handler.end();

deleEnd();

} else deleEnd(handler.end());

}

emitBlockStart(title);

for (int i = 0; i < input.length; ++i) {

// emit end when on same or lower indent level, number based on difference

// start on new lines

switch (input[i]) {

case '\n':

//stack[0] & current_bits;

// FIXME: Start and end based on "-"

const nodeContent = input[line_start_index..i];

import std.stdio;

emitBlockStart(nodeContent);

i++;

line_start_index = i;

int new_indent_level =

count_indents(i, input, spaces_per_indent);

line_content_start_index = i;

const extraEndings = i == input.length ? 0 : 1;

foreach (_;

0..current_indent_level - new_indent_level + extraEndings) {

emitBlockEnd();

}

if (relaxed && new_indent_level > current_indent_level + 1) {

foreach (_; 0..new_indent_level - current_indent_level - 1)

{

emitBlockStart("");

}

current_indent_level = new_indent_level;

break;

case '[':

break;

// Skip across multiline constructs to prevent

// detect_indent

case '`':

if (input[i+1] == '`' && input[i+2] == '`') {

// Skip 3 at a time for efficiency

// TODO: SIMD this and/or PGO it

for (i += 3; i < input.length; ++i) {

if (input[i-2] == '`' &&

input[i-1] == '`' &&

input[i-0] == '`') {

break;

}

break;

default: break;

}

if (line_content_start_index != input.length) {

emitBlockStart(input[line_start_index .. input.length]);

}

for (int i = 0; i < current_indent_level + 1; ++i) {

emitBlockEnd();

}

// End again because we started for the title

emitBlockEnd();

}

/// Test the stream of parser events

unittest {

import std.range, std.array;

struct ExampleParseEventHandler {

string start(string text) {

return "START" ~ text;

}

string end() {

return "END";

}

string sample = "- ab\n\t- b\nhello\n\tworld\n\tfoo";

// A trailing newline should not affect ther esult

foreach (useTrailingNewline; [false, true]) {

string result;

parse!(ExampleParseEventHandler, s => result ~= s, s => result ~= s)

(sample ~ (useTrailingNewline ? "\n" : ""), 4, "Title");

import std.stdio;

debug writeln(result);

assert(result ==

"STARTTitleSTART- abSTART\t- bENDENDSTARThelloSTART\tworldENDSTART\tfooENDENDEND"

);

}

struct A {

}

private struct WithConstructor {

string[] member;

this(string[] arg, A a) {

member = arg;

}

void start(string text) {

}

void end() {

}

unittest {

A a;

parse!(WithConstructor)

("Test", 4, "Title", ["arg"], a);

}

unittest {

import std.stdio;

struct ExampleParseEventHandler {

string start(string text) {

return "<div>" ~ text;

}

string end() {

return "</div>";

}

string sample =

d`;

string result;

parse!(ExampleParseEventHandler, s => result ~= s, s => result ~= s, true)

(sample, 1, "Title");

writeln(result);

assert(result == "<div>Title<div>a<div><div> b</div></div></div><div>c<div><div><div> d</div></div></div></div></div>");

}

struct ConvertToXMLEventHandler {

string start(string text) {

return "<block>" ~ text;

}

string end() {

return "</block>";

}

/*struct ConvertToOPMLEventHandler {

string start(string text) {

// todo: escpae

return `<outline text=` ~ text;

}

string end() {

return `</outline>`;

}

}*/

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