From 7e314bd12e4aa8ea9742b1e4765f3fe65de38c2d Mon Sep 17 00:00:00 2001
From: Matt Farina <matt@mattfarina.com>
Date: Wed, 18 Nov 2020 12:22:36 -0500
Subject: [PATCH] Forcing ordered operation when generating regex

Range was used to iterate over the operations as part of generating
the regex. Range iterations are random. There were cases where the
empty key caused the regex to be generated as invalid.

This change removes the range so that the order is always the same.

Closes #155
---
 .github/workflows/test.yaml |  2 +-
 constraints.go              | 11 ++++-------
 2 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/.github/workflows/test.yaml b/.github/workflows/test.yaml
index d484edb..cc4ba21 100644
--- a/.github/workflows/test.yaml
+++ b/.github/workflows/test.yaml
@@ -4,7 +4,7 @@ jobs:
   test:
     strategy:
       matrix:
-        go-version: [1.12.x, 1.13.x, 1.14.x]
+        go-version: [1.12.x, 1.13.x, 1.14.x, 1.15.x]
         platform: [ubuntu-latest, macos-latest, windows-latest]
     runs-on: ${{ matrix.platform }}
     steps:
diff --git a/constraints.go b/constraints.go
index 7420823..547613f 100644
--- a/constraints.go
+++ b/constraints.go
@@ -164,14 +164,11 @@ func init() {
 		"^":  constraintCaret,
 	}
 
-	ops := make([]string, 0, len(constraintOps))
-	for k := range constraintOps {
-		ops = append(ops, regexp.QuoteMeta(k))
-	}
+	ops := `=||!=|>|<|>=|=>|<=|=<|~|~>|\^`
 
 	constraintRegex = regexp.MustCompile(fmt.Sprintf(
 		`^\s*(%s)\s*(%s)\s*$`,
-		strings.Join(ops, "|"),
+		ops,
 		cvRegex))
 
 	constraintRangeRegex = regexp.MustCompile(fmt.Sprintf(
@@ -180,12 +177,12 @@ func init() {
 
 	findConstraintRegex = regexp.MustCompile(fmt.Sprintf(
 		`(%s)\s*(%s)`,
-		strings.Join(ops, "|"),
+		ops,
 		cvRegex))
 
 	validConstraintRegex = regexp.MustCompile(fmt.Sprintf(
 		`^(\s*(%s)\s*(%s)\s*\,?)+$`,
-		strings.Join(ops, "|"),
+		ops,
 		cvRegex))
 }