lib/parse-sexp: parse single terms and the empty list.

There is not much of a parser here yet, but it already does some
useful error reporting. Most functionality sketched in the
documentation is not implemented yet; detailed documentation will
follow with the implementation.

1 files changed, 81 insertions, 0 deletions

diff --git a/doc/man7/notmuch-sexp-queries.rst b/doc/man7/notmuch-sexp-queries.rst
new file mode 100644
index 00000000..1118f854
--- /dev/null
+++ b/doc/man7/notmuch-sexp-queries.rst
@@ -0,0 +1,81 @@
+.. _notmuch-sexp-queries(7):
+
+====================
+notmuch-sexp-queries
+====================
+
+SYNOPSIS
+========
+
+**notmuch** **search** ``--query=sexp`` '(and (to santa) (date december))'
+
+DESCRIPTION
+===========
+
+
+S-EXPRESSIONS
+-------------
+
+An *s-expression* is either an atom, or list of whitespace delimited
+s-expressions inside parentheses. Atoms are either
+
+*basic value*
+    A basic value is an unquoted string containing no whitespace, double quotes, or
+    parentheses.
+
+*quoted string*
+    Double quotes (") delimit strings possibly containing whitespace
+    or parentheses. These can contain double quote characters by
+    escaping with backslash. E.g. ``"this is a quote \""``.
+
+S-EXPRESSION QUERIES
+--------------------
+
+An s-expression query is either an atom, the empty list, or a
+*compound query* consisting of a prefix atom (first element) defining
+a *field*, *logical operation*, or *modifier*, and 0 or more
+subqueries.
+
+``*``
+``()``
+    The empty list matches all messages
+
+*term*
+    Match all messages containing *term*, possibly after stemming
+    or phase splitting.
+
+``(`` *field* |q1| |q2| ... |qn| ``)``
+    Restrict the queries |q1| to |qn| to *field*, and combine with *and*
+    (for most fields) or *or*. See :any:`fields` for more information.
+
+``(`` *operator* |q1| |q2| ... |qn| ``)``
+    Combine queries |q1| to |qn|. See :any:`operators` for more information.
+
+``(`` *modifier* |q1| |q2| ... |qn| ``)``
+    Combine queries |q1| to |qn|, and reinterpret the result (e.g. as a regular expression).
+    See :any:`modifiers` for more information.
+
+.. _fields:
+
+FIELDS
+``````
+
+.. _operators:
+
+OPERATORS
+`````````
+
+.. _modifiers:
+
+MODIFIERS
+`````````
+
+EXAMPLES
+========
+
+``Wizard``
+    Match all messages containing the word "wizard", ignoring case.
+
+.. |q1| replace:: :math:`q_1`
+.. |q2| replace:: :math:`q_2`
+.. |qn| replace:: :math:`q_n`