From ad7099be6164c428de5b6c227577047dc0fd865e Mon Sep 17 00:00:00 2001
From: "Steven G. Johnson" <stevenj@mit.edu>
Date: Fri, 16 Mar 2018 12:47:06 -0400
Subject: [PATCH] prepend leading 0 if needed

---
 README.md             | 14 ++++++++++----
 src/VersionParsing.jl | 18 +++++++++---------
 test/runtests.jl      |  4 +++-
 3 files changed, 22 insertions(+), 14 deletions(-)

diff --git a/README.md b/README.md
index 488477e..ab96f82 100644
--- a/README.md
+++ b/README.md
@@ -10,12 +10,18 @@ version-number strings into Julia's built-in `VersionNumber` type, via
 the `vparse(string)` function.
 
 Unlike the `VersionNumber(string)` constructor, `vparse(string)` can
-handle version-number strings in a much wider range of formats.  For example,
+handle version-number strings in a much wider range of formats than
+are encompassed by the [semver standard](https://semver.org/).  This
+is useful in order to support `VersionNumber` comparisons applied
+to "foreign" version numbers from external packages.
+
+For example,
 
-* `major.minor.patch[.+-]something[.+-]something` is converted if possible into the
-  closest `VersionNumber` equivalent (`something` becomes a prerelease
-  or build identifier).
 * Non-numeric prefixes are stripped along with any invalid version characters.
 * Text following whitespace after the version number is ignored.
+* `major.minor.patch.x.y.z` is supported, with `x.y.z` prepended to the
+  semver build identifier, i.e. it is parsed like `major.minor.patch+x.y.z`.
+* Multiple `+x+y` build identifiers are concatenated as if they were `+x.y`.
+* A leading `0` is prepended if needed, e.g. `.x` is treated as `0.x`.
 * When all else fails, everything except the first `major.minor.patch`
   digits found are ignored.
diff --git a/src/VersionParsing.jl b/src/VersionParsing.jl
index b33ed32..eb0ac9f 100644
--- a/src/VersionParsing.jl
+++ b/src/VersionParsing.jl
@@ -15,18 +15,17 @@ export vparse
     vparse(s::AbstractString)
 
 Returns a `VersionNumber` representing as much as possible of the version
-information in the string `s`.
+information in the string `s`.  A much wider range of formats is supported
+than the semver styles recognized by `VersionNumber(s)`.
 
-Typically, `s` is a string of the form `"major[.minor.patch]"`, but several
-variations on this format are supported, including:
+For example,
 
-* `major.minor.patch[.+-]something[.+-]something` is converted if possible into the
-  closest `VersionNumber` equivalent (`something` becomes a prerelease
-  or build identifier).
 * Non-numeric prefixes are stripped along with any invalid version characters.
 * Text following whitespace after the version number is ignored.
-* In Debian-style version numbers `epoch:major.minor.patch-rev`, the "epoch"
-  is ignored and only the upstream version `major.minor.patch-rev` is used.
+* `major.minor.patch.x.y.z` is supported, with `x.y.z` prepended to the
+  semver build identifier, i.e. it is parsed like `major.minor.patch+x.y.z`.
+* Multiple `+x+y` build identifiers are concatenated as if they were `+x.y`.
+* A leading `0` is prepended if needed, e.g. `.x` is treated as `0.x`.
 * When all else fails, everything except the first `major.minor.patch`
   digits found are ignored.
 """
@@ -36,8 +35,9 @@ digits2num(s::AbstractString) = all(isdigit, s) ? parse(Int, s) : s
 splitparts(s::AbstractString) = map(digits2num, filter!(!isempty, split(s, '.')))
 
 function vparse(s_::String)
-    s = replace(s_, r"^\D+"=>"") # strip non-numeric prefix
+    s = replace(s_, r"^[^0-9.]+"=>"") # strip non-numeric prefix
     isempty(s) && throw(ArgumentError("non-numeric version string $s_"))
+    contains(s, r"^\.\d") && (s = "0" * s) # treat .x as 0.x
     if contains(s, r"^\d:\d+") # debian-style version number
         s = replace(s, r"^\d:"=>"") # strip epoch
     end
diff --git a/test/runtests.jl b/test/runtests.jl
index 7feea47..f07bdbd 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -8,7 +8,7 @@ using Compat.Test
 # examples from npm docs (https://docs.npmjs.com/misc/semver)
 @test_throws ArgumentError vparse("a.b.c")
 @test vparse("  =v1.2.3   ") == v"1.2.3"
-@test vparse("v2") == v"2.0.0"
+@test vparse("v2") == vparse("version 2.0") == v"2.0.0"
 @test vparse("42.6.7.9.3-alpha") == v"42.6.7-alpha+9.3"
 
 @test vparse("1.2.3.8-4.2") == v"1.2.3-4.2+8"
@@ -16,3 +16,5 @@ using Compat.Test
 
 # Debian-style epoch:upstream version numbers
 @test vparse("4:4.7.4-0ubuntu8") == vparse("0:4.7.4-0ubuntu8") == v"4.7.4-0ubuntu8"
+
+@test vparse(".3") == v"0.3.0"