Switch the README file to reStructuredText

Author: SimonSapin

README

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+Result representation
+=====================
+
+AST nodes (the results of parsing) are represented in JSON as follow.
+This representation was chosen to be compact
+(and thus less annoying to write by hand)
+while staying unambiguous.
+For example, the difference between @import and \@import is not lost:
+they are represented as ``["at-keyword", "import"]`` and ``["ident", "@import"]``,
+respectively.
+
+
+Component values
+----------------
+
+<ident>
+    Array of length 2: the string ``"ident"``, and the value as a string.
+
+<at-keyword>
+    Array of length 2: the string ``"at-keyword"``, and the value as a string.
+
+<hash>
+    Array of length 3: the string ``"hash"``, the value as a string,
+    and the type as the string ``"id"`` or ``"unrestricted"``.
+
+<string>
+    Array of length 2: the string ``"string"``, and the value as a string.
+
+<bad-string>
+    Array of length 1: the string ``"bad-string"``.
+
+<url>
+    Array of length 2: the string ``"url"``, and the value as a string.
+
+<bad-url>
+    Array of length 1: the string ``"bad-url"``.
+
+<delim>
+    The value as a one-character string.
+
+<number>
+    Array of length 4: the string ``"number"``, the representation as a string,
+    the value as a number, and the type as the string ``"integer"`` or ``"number"``.
+
+<percentage>
+    Array of length 4: the string ``"percentage"``, the representation as a string,
+    the value as a number, and the type as the string ``"integer"`` or ``"number"``.
+
+<dimension>
+    Array of length 4: the string ``"dimension"``, the representation as a string,
+    the value as a number, the type as the string ``"integer"`` or ``"number"``,
+    and the unit as a string.
+
+<unicode-range>
+    Array of length 2: the string ``"unicode-range"``, and the range as either
+    null for the empty range, or an array of two numbers.
+
+<include-match>
+    The string ``"~="``.
+
+<dash-match>
+    The string ``"|="``.
+
+<prefix-match>
+    The string ``"^="``.
+
+<suffix-match>
+    The string ``"$="``.
+
+<substring-match>
+    The string ``"*="``.
+
+<column>
+    The string ``"||"``.
+
+<whitespace>
+    The string ``" "`` (a single space.)
+
+<CDO>
+    The string ``"<!--"``.
+
+<CDC>
+    The string ``"-->"``.
+
+<colon>
+    The string ``":"``.
+
+<semicolon>
+    The string ``";"``.
+
+<comma>
+    The string ``","``.
+
+{} block
+    An array of length N+1: the string ``"{}"``
+    followed by the N component values of the block’s value.
+
+[] block
+    An array of length N+1: the string ``"[]"``
+    followed by the N component values of the block’s value.
+
+() block
+    An array of length N+1: the string ``"()"``
+    followed by the N component values of the block’s value.
+
+Function
+    An array of length N+2: the string ``"function"``
+    and the name of the function as a string
+    followed by the N component values of the function’s value.
+
+
+Other nodes
+-----------
+
+Declaration
+    An array of length 4: the string ``"declaration"``, the name as a string,
+    the value as a nested array of component values,
+    and a the important flag as a boolean.
+
+At-rule
+    An array of length 4: the string ``"at-rule"``,
+    the name (value of the at-keyword) as a string,
+    the prelude as a nested array of component values,
+    and the optional block as a nested array of component value, or null.
+
+Qualified rule
+    An array of length 3: the string ``"qualified rule"``,
+    the prelude as a nested array of component values,
+    and the block as a nested array of component value.