From 83cd6074b88fc88dd05992f516ba144118b5d5d0 Mon Sep 17 00:00:00 2001
From: Danny Robson <danny@nerdcruft.net>
Date: Tue, 19 Mar 2019 17:09:03 +1100
Subject: [PATCH] parse/time: add consuming and non-consuming parsers

---
 parse/time.cpp      | 21 ++++++++++++++++++++-
 parse/time.hpp      | 13 +++++++++++--
 test/parse/time.cpp |  5 ++---
 3 files changed, 33 insertions(+), 6 deletions(-)

diff --git a/parse/time.cpp b/parse/time.cpp
index 923b7fb6..a0665a00 100644
--- a/parse/time.cpp
+++ b/parse/time.cpp
@@ -91,7 +91,7 @@ try_consume_prefix (
 
 ///////////////////////////////////////////////////////////////////////////////
 cruft::expected<std::chrono::nanoseconds, std::errc>
-cruft::parse::duration (cruft::view<char const*> &remain)
+cruft::parse::duration::consume (cruft::view<char const*> &remain)
 {
     auto const count = value<std::intmax_t> (remain);
     if (remain.empty ())
@@ -128,3 +128,22 @@ cruft::parse::duration (cruft::view<char const*> &remain)
 
     return cruft::unexpected (std::errc::invalid_argument);
 }
+
+
+//-----------------------------------------------------------------------------
+cruft::expected<std::chrono::nanoseconds, std::errc>
+cruft::parse::duration::from (cruft::view<char const*> const &str)
+{
+    auto remain = str;
+
+    // Try to parse from the temporary view.
+    auto res = ::cruft::parse::duration::consume (remain);
+    if (!res)
+        return res;
+
+    // Ensure it was totally consumed.
+    if (!remain.empty ())
+        return cruft::unexpected (std::errc::invalid_argument);
+
+    return res;
+}
diff --git a/parse/time.hpp b/parse/time.hpp
index fff460ef..e4b156f2 100644
--- a/parse/time.hpp
+++ b/parse/time.hpp
@@ -14,14 +14,23 @@
 #include <chrono>
 #include <system_error>
 
-namespace cruft::parse {
+namespace cruft::parse::duration {
     /// Parse a number that represents a duration. eg, "1s", "5 minutes".
     ///
+    /// The data view is updated to indicate the unused data.
+    ///
     /// When there is no suffix it is assumed the quantity is in second.
     ///
     /// Note: The quantities are as defined by the standard std::chrono
     /// durations. This means that "1 month" will equal just under 30.5 days.
     /// Thus the utility is not universally useful for offsetting.
     expected<std::chrono::nanoseconds, std::errc>
-    duration (cruft::view<char const*> &);
+    consume (cruft::view<char const*> &);
+
+
+    /// Parse a number that represent a duration (as with `consume`).
+    ///
+    /// The operation will fail if the entire input is not consumed.
+    expected<std::chrono::nanoseconds, std::errc>
+    from (cruft::view<char const*> const&);
 }
diff --git a/test/parse/time.cpp b/test/parse/time.cpp
index 0cd71967..666f3458 100644
--- a/test/parse/time.cpp
+++ b/test/parse/time.cpp
@@ -36,9 +36,8 @@ int main ()
     cruft::TAP::logger tap;
 
     for (auto const &[str,val,msg]: TESTS) {
-        cruft::view src (str);
-        auto res = cruft::parse::duration (src);
-        tap.expect (src.empty () && res && val == *res, "%! %! == %!", msg, val.count (), res->count());
+        auto res = cruft::parse::duration::from (str);
+        tap.expect (res && val == *res, "%! %! == %!", msg, val.count (), res->count());
     }
 
     return tap.status ();