txr-case: upkeep.

* share/txr/stdlib/txr-case.tl (txr-case-impl): If the input
is a stream, then convert it to a lazy list of lines, so that
running multiple functions against it produces sane,
backtracking behavior, like a @(cases) construct.

* tests/011/txr-case.expected: Updated.

* tests/011/txr-case.txr: Now actually contains a test case
for txr-case.

* txr.1: Address an issue reported by Paul A. Patience: the
input to match-fun, txr-if and txr-when may be a stream. That
has always been the case in the implementation. Also document
that when the input is a single string, it is treated as a
list. Document the new requirement in txr-case that a stream
is converted into lazy list of lines.

4 files changed, 48 insertions, 5 deletions

diff --git a/share/txr/stdlib/txr-case.tl b/share/txr/stdlib/txr-case.tl
index 4f51ea48..244c58b7 100644
--- a/share/txr/stdlib/txr-case.tl
+++ b/share/txr/stdlib/txr-case.tl
@@ -65,4 +65,6 @@
 (defmacro txr-case (input-expr . clauses)
   (let ((input (gensym "input-")))
     ^(let ((,input ,input-expr))
+       (if (streamp ,input)
+         (set ,input (get-lines ,input)))
        (txr-case-impl ,input ,*clauses))))
diff --git a/tests/011/txr-case.expected b/tests/011/txr-case.expected
index 4af473e5..e7582780 100644
--- a/tests/011/txr-case.expected
+++ b/tests/011/txr-case.expected
@@ -2,3 +2,4 @@ no match for 09-10-20
 match: year 2009, month 10, day 20
 no match for July-15-2014
 no match for foo
+match: year 2021, month 06, day 16, foo:bar
diff --git a/tests/011/txr-case.txr b/tests/011/txr-case.txr
index 1aa80478..aa234ed8 100644
--- a/tests/011/txr-case.txr
+++ b/tests/011/txr-case.txr
@@ -7,3 +7,15 @@
      (txr-if date (y m d) date
        (put-line `match: year @y, month @m, day @d`)
        (put-line `no match for @date`))))
+@(define notmatch ())
+blah
+@(end)
+@(define stuff (year month day a b))
+@(date year month day)
+@a @b
+@(end)
+@(do (txr-case (make-strlist-input-stream '("2021-06-16"
+                                            "foo bar"))
+
+       (notmatch () (put-line "notexpected"))
+       (stuff (y m d a b) (put-line `match: year @y, month @m, day @d, @a:@b`))))
diff --git a/txr.1 b/txr.1
index 5a633d4c..1883130c 100644
--- a/txr.1
+++ b/txr.1
@@ -71237,11 +71237,17 @@ which will be interpreted as pattern variables, and may be bound or unbound.
 If they are not symbols, then they are treated as expressions (of the
 pattern language, not \*(TL) and evaluated accordingly.
 
-The
+The optional
 .meta input
-argument is a list of strings, which may be lazy. It represents the
-lines of the text stream to be processed. If omitted, it defaults to
-.codn nil .
+argument is an object of one of several types. It may be a stream,
+character string or list of strings.  If it is a string, then
+it is converted to a list containing that string.
+A list of strings represents zero or more lines of text to be
+processed.  If the
+.meta input
+argument is omitted, then it defaults to
+.codn nil ,
+interpreted as an empty list of lines.
 
 The
 .meta files
@@ -71353,7 +71359,11 @@ macro invokes the \*(TX pattern matching function
 .meta name
 on some input given by the
 .meta input
-parameter, which is a list of strings, or a single string.
+parameter, whose semantics are the same as the
+.meta input
+argument of the
+.code match-fun
+funtion.
 
 If
 .meta name
@@ -71515,6 +71525,24 @@ otherwise the forms are evaluated in order and the value of the last
 one specifies the result of
 .codn txr-case .
 
+The value of the input
+.meta input-form
+is expected to be one of the same kinds of objects as given by the
+requirements for the
+.meta input
+argument of the
+.code match-fun
+functions.
+
+If
+.meta input-form
+evaluates to a stream object according to the
+.code streamp
+function, then the stream is converted to a lazy list of lines,
+as if by invoking the
+.code get-lines
+function on that stream; that list then serves as input to the clauses.
+
 .coNP Function @ txr-parse
 .synb
 .mets (txr-parse >> [ source >> [ error-stream