////////////////////////////////
// Unlabeled Sets

//(MD_NodeFlag_HasParenLeft|MD_NodeFlag_HasParenRight)
(foo bar)
(
foo
bar
)
()

//(MD_NodeFlag_HasBracketLeft|MD_NodeFlag_HasBracketRight)
[foo bar]

//(MD_NodeFlag_HasBracketLeft|MD_NodeFlag_HasParenRight)
[foo bar)

//(MD_NodeFlag_HasParenLeft|MD_NodeFlag_HasBracketRight)
(foo bar]

//(MD_NodeFlag_HasBraceLeft|MD_NodeFlag_HasBraceRight)
{foo bar}

/*
** Mixing { with ) or ] generates an error.
** Same with ( or [ with }.
** This is itended to make {} a useful way to delimit a set when extra help
** via errors from the parser is preferable to flexibility.
*/

////////////////////////////////
// Labeled Sets

foo: (bar baz) 123: (foo bar)
"foo": (bar baz) +++: (foo bar)
foo: ()

"""
foo
""": (bar baz)

foo: [bar]
foo: [foo)
foo: (bar]
foo: {bar}

/*
** When a set has a label, it's node will have the label as it's string
** contents, and the children as it's set contnts. The node will have flags
** for both it's label and it's set properties. For instance the root node 
** parsed from 
**                  +++: (foo bar) 
** has the flags:
**  MD_NodeFlag_HasParenLeft|MD_NodeFlag_HasParenRight|MD_NodeFlag_Symbol
*/

////////////////////////////////
// Nested Sets

{
  (foo bar)
  foo: (bar)
  [a b c]
  [({})]
}

////////////////////////////////
// Undelimited Sets (<no left/right flags>)

// delimited by newline
foo: bar baz

// starts on the next line, delimited by new line
foo:
bar baz

// starts on the next line, consumes entire multi-line string
foo:
"""
bar
"""

// kind of weird, but you can chain things on so long as a newline
// never appears outside of a multi-line string to end the set
foo: """
bar
""" baz """
and-back-to-foo-again
"""

// nesting undelimited sets
foo: bar:
baz: foo_again

// undelimited sets may not contain unlabeled delimited sets
// the following forms one undelimited set followed by a delimited set
// the delimited set is a sibling to foo, not a child to foo.
// this also emits a warning because it's weird.
foo: bar (baz)

// undelimited sets *may* however contain labeled delimited sets
// now foo is an undelimited set that contains bar, and bar is a
// delimited set that contains baz
foo: bar: (baz)

// again things can get weird. Here bar and baz are both delimited
// sets contained in foo, because at there are no newlines at the
// level of the foo node until after the baz set.
foo:
bar: (
 a 
 b
 c
) baz: (
 1
 2
 3
)

////////////////////////////////
// Seperators

// A separator can be placed after any member of delimited sets.
// The separator does not effect the shape of the tree but it does
// attach flags to the nodes before and after it.

(
 word1
 //(MD_NodeFlag_IsBeforeComma)
 word2,
 //(MD_NodeFlag_IsBeforeComma|MD_NodeFlag_IsAfterComma)
 word3,
 //(MD_NodeFlag_IsAfterComma)
 word4
)

(
 word1
 //(MD_NodeFlag_IsBeforeSemicolon)
 word2;
 //(MD_NodeFlag_IsBeforeSemicolon|MD_NodeFlag_IsAfterSemicolon)
 word3;
 //(MD_NodeFlag_IsAfterSemicolon)
 word4
)

(
 word1
 //(MD_NodeFlag_IsBeforeComma)
 word2,
 //(MD_NodeFlag_IsBeforeSemicolon|MD_NodeFlag_IsAfterComma)
 word3;
 //(MD_NodeFlag_IsAfterSemicolon|MD_NodeFlag_IsBeforeComma)
 word4,
)

// A separator ends an undelimited set early. Here the commas and semi-colon
// split this line into three undelimited sets. The "before" flag goes on the
// undelimited set, not the child. For instance, here the set foo gets the flag
// (MD_NodeFlag_IsBeforeComma)
foo: bar,    baz: foo_again;    foo: bar


////////////////////////////////
// Tags

// tags are made with an @ before identifier
@foo bar

// tags can be attached to any node
@foo "string"

// any number of tags can be attached to a node
@foo @bar @foo @bar baz

// tags can be attached to sets
@foo (bar baz)
@foo [bar baz]
@foo bar: {baz}
@foo bar: baz

// tags can be attached to nodes inside sets
@foo (@bar baz)
@foo bar: @baz foo_again

// tags can have children of their own 
// set with () and no space after the identifier
@foo(bar) baz
@foo(bar) (baz baz)
@foo(bar bar) foo
@foo(bar baz) @bar fooz

// the children of a tag can be sets
@foo({bar baz} [biz boo]) far
@foo(bar: baz: 123) xyz

// the children of a tag are actually just a set delimited with ()
@tag(tag_child, 123;
     "strings etc") node

// the children of a tag can even be tagged
@tag(tag_child, @number 123) node
@tag(tag_child, @number(integer) 123) node