Add support for variables in workflow files.

README.md

@@ -52,10 +52,12 @@ The SpdxTool can be driven using workflow yaml files of the following format:
 ```yaml
 steps:
 - command: <command-name>
-  <arguments mapping>
+  inputs:
+    <arguments mapping>
 
 - command: <command-name>
-  <arguments mapping>
+  inputs:
+    <arguments mapping>
 ```
 
 ## YAML Commands
@@ -67,24 +69,30 @@ steps:
 
   # Run a separate workflow file
 - command: run-workflow
-  file: other-workflow-file.yaml
+  inputs:
+    file: other-workflow-file.yaml
+    parameters:
+      <optional parameters>
 
   # Create a summary markdown from the specified SPDX document
 - command: to-markdown
-  spdx: input.spdx.json
-  markdown: output.md
+  inputs:
+    spdx: input.spdx.json
+    markdown: output.md
 
   # Rename the SPDX-ID of an element in an SPDX document
 - command: rename-id
-  spdx: <spdx.json>
-  old: <old-id>
-  new: <new-id>
+  inputs:
+    spdx: <spdx.json>
+    old: <old-id>
+    new: <new-id>
 
   # Copy a package from one SPDX document to another SPDX document  
 - command: copy-package
-  from: <from.spdx.json>
-  to: <to.spdx.json>
-  package: <package>
-  relationship: <relationship>
-  element: <element>
+  inputs:
+    from: <from.spdx.json>
+    to: <to.spdx.json>
+    package: <package>
+    relationship: <relationship>
+    element: <element>
 ```

src/DemaConsulting.SpdxTool/Commands/Command.cs

@@ -17,5 +17,88 @@ public abstract class Command
     /// Run the command
     /// </summary>
     /// <param name="step">Command step</param>
-    public abstract void Run(YamlMappingNode step);
-}
+    /// <param name="variables">Workflow variables</param>
+    public abstract void Run(YamlMappingNode step, Dictionary<string, string> variables);
+
+    /// <summary>
+    /// Expand variables in text
+    /// </summary>
+    /// <param name="text">Text to expand</param>
+    /// <param name="variables">Variables</param>
+    /// <returns>Expanded text</returns>
+    /// <exception cref="InvalidOperationException">on error</exception>
+    public static string Expand(string text, Dictionary<string, string> variables)
+    {
+        while (true)
+        {
+            // Find the last macro to expand
+            var start = text.LastIndexOf("${{", StringComparison.Ordinal);
+            if (start < 0)
+                return text;
+
+            // Find the end of the macro
+            var end = text.IndexOf("}}", start, StringComparison.Ordinal);
+            if (end < 0)
+                throw new InvalidOperationException("Unmatched '${{' in variable expansion");
+
+            // Get the variable name
+            var name = text[(start + 3)..end].Trim();
+
+            // Replace the variable
+            if (!variables.TryGetValue(name, out var value))
+                throw new InvalidOperationException($"Undefined variable {name}");
+
+            // Apply the replacement
+            text = text[..start] + value + text[(end + 2)..];
+        }
+    }
+
+    /// <summary>
+    /// Get a map from a map
+    /// </summary>
+    /// <param name="map">Parent map node</param>
+    /// <param name="name">Entry name</param>
+    /// <returns>Child map node or null</returns>
+    public static YamlMappingNode? GetMapMap(YamlMappingNode? map, string name)
+    {
+        // Handle null map
+        if (map == null)
+            return null;
+
+        // Get the entry
+        return map.Children.TryGetValue(name, out var value) ? value as YamlMappingNode : null;
+    }
+
+    /// <summary>
+    /// Get a sequence from a map
+    /// </summary>
+    /// <param name="map">Parent map node</param>
+    /// <param name="name">Entry name</param>
+    /// <returns>Child sequence node or null</returns>
+    public static YamlSequenceNode? GetMapSequence(YamlMappingNode? map, string name)
+    {
+        // Handle null map
+        if (map == null)
+            return null;
+
+        // Get the entry
+        return map.Children.TryGetValue(name, out var value) ? value as YamlSequenceNode : null;
+    }
+
+    /// <summary>
+    /// Get a map value from a map
+    /// </summary>
+    /// <param name="map">Map node</param>
+    /// <param name="key">Map key</param>
+    /// <param name="variables">Variables for expansion</param>
+    /// <returns>Map value or null</returns>
+    public static string? GetMapString(YamlMappingNode? map, string key, Dictionary<string, string> variables)
+    {
+        // Handle null map
+        if (map == null)
+            return null;
+
+        // Get the parameter
+        return map.Children.TryGetValue(key, out var value) ? Expand(value.ToString(), variables) : null;
+    }
+}

src/DemaConsulting.SpdxTool/Commands/CopyPackageCommand.cs

@@ -31,11 +31,12 @@ public class CopyPackageCommand : Command
             "",
             "From a YAML file this can be used as:",
             "  - command: copy-package",
-            "    from: <from.spdx.json>",
-            "    to: <to.spdx.json>",
-            "    package: <package>",
-            "    relationship: <relationship>",
-            "    element: <element>",
+            "    inputs:",
+            "      from: <from.spdx.json>",
+            "      to: <to.spdx.json>",
+            "      package: <package>",
+            "      relationship: <relationship>",
+            "      element: <element>",
             "",
             "The <package> argument is the name of a package in <from.spdx.json> to copy.",
             "The <relationship> argument describes the <element> relationship to <package>.",
@@ -65,31 +66,33 @@ public override void Run(string[] args)
     }
 
     /// <inheritdoc />
-    public override void Run(YamlMappingNode step)
+    public override void Run(YamlMappingNode step, Dictionary<string, string> variables)
     {
-        // Get the from-filename
-        if (!step.Children.TryGetValue("from", out var fromFile))
-            throw new YamlException(step.Start, step.End, "'copy-package' command missing 'from' parameter");
+        // Get the step inputs
+        var inputs = GetMapMap(step, "inputs");
 
-        // Get the to-filename
-        if (!step.Children.TryGetValue("to", out var toFile))
-            throw new YamlException(step.Start, step.End, "'copy-package' command missing 'to' parameter");
+        // Get the 'from' input
+        var fromFile = GetMapString(inputs, "from", variables) ??
+                       throw new YamlException(step.Start, step.End, "'copy-package' missing 'from' input");
 
-        // Get the package name
-        if (!step.Children.TryGetValue("package", out var package))
-            throw new YamlException(step.Start, step.End, "'copy-package' command missing 'package' parameter");
+        // Get the 'to' input
+        var toFile = GetMapString(inputs, "to", variables) ??
+                     throw new YamlException(step.Start, step.End, "'copy-package' missing 'to' input");
 
-        // Get the relationship type
-        if (!step.Children.TryGetValue("relationship", out var relationship))
-            throw new YamlException(step.Start, step.End, "'copy-package' command missing 'relationship' parameter");
+        // Get the 'package' input
+        var package = GetMapString(inputs, "package", variables) ??
+                      throw new YamlException(step.Start, step.End, "'copy-package' missing 'package' input");
 
-        // Get the element name
-        if (!step.Children.TryGetValue("element", out var element))
-            throw new YamlException(step.Start, step.End, "'copy-package' command missing 'element' parameter");
+        // Get the 'relationship' input
+        var relationship = GetMapString(inputs, "relationship", variables) ??
+                           throw new YamlException(step.Start, step.End, "'copy-package' missing 'relationship' input");
+
+        // Get the 'element' input
+        var element = GetMapString(inputs, "element", variables) ??
+                      throw new YamlException(step.Start, step.End, "'copy-package' missing 'element' input");
 
         // Copy the package
-        CopyPackage(fromFile.ToString(), toFile.ToString(), package.ToString(), relationship.ToString(),
-            element.ToString());
+        CopyPackage(fromFile, toFile, package, relationship, element);
     }
 
     /// <summary>

src/DemaConsulting.SpdxTool/Commands/HelpCommand.cs

@@ -29,7 +29,8 @@ public class HelpCommand : Command
             "",
             "From a YAML file this can be used as:",
             "  - command: help",
-            "    about: <command>"
+            "    inputs:",
+            "      about: <command>"
         },
         Instance);
 
@@ -52,14 +53,17 @@ public override void Run(string[] args)
     }
 
     /// <inheritdoc />
-    public override void Run(YamlMappingNode step)
+    public override void Run(YamlMappingNode step, Dictionary<string, string> variables)
     {
-        // Get the about command
-        if (!step.Children.TryGetValue("about", out var about))
-            throw new YamlException(step.Start, step.End, "'help' command missing 'about' parameter");
+        // Get the step inputs
+        var inputs = GetMapMap(step, "inputs");
+
+        // Get the 'about' input
+        var about = GetMapString(inputs, "about", variables) ??
+                    throw new YamlException(step.Start, step.End, "'help' command missing 'about' input");
 
         // Generate the markdown
-        ShowUsage(about.ToString());
+        ShowUsage(about);
     }
 
     /// <summary>

src/DemaConsulting.SpdxTool/Commands/RenameIdCommand.cs

@@ -30,9 +30,10 @@ public class RenameIdCommand : Command
             "",
             "From a YAML file this can be used as:",
             "  - command: rename-id",
-            "    spdx: <spdx.json>",
-            "    old: <old-id>",
-            "    new: <new-id>"
+            "    inputs:",
+            "      spdx: <spdx.json>",
+            "      old: <old-id>",
+            "      new: <new-id>"
         },
         Instance);
 
@@ -55,22 +56,25 @@ public override void Run(string[] args)
     }
 
     /// <inheritdoc />
-    public override void Run(YamlMappingNode step)
+    public override void Run(YamlMappingNode step, Dictionary<string, string> variables)
     {
-        // Get the spdx filename
-        if (!step.Children.TryGetValue("spdx", out var spdxFile))
-            throw new YamlException(step.Start, step.End, "'rename-id' command missing 'spdx' parameter");
+        // Get the step inputs
+        var inputs = GetMapMap(step, "inputs");
 
-        // Get the old ID
-        if (!step.Children.TryGetValue("old", out var oldId))
-            throw new YamlException(step.Start, step.End, "'rename-id' command missing 'old' parameter");
+        // Get the 'spdx' input
+        var spdxFile = GetMapString(inputs, "spdx", variables) ??
+                       throw new YamlException(step.Start, step.End, "'rename-id' command missing 'spdx' input");
 
-        // Get the new ID
-        if (!step.Children.TryGetValue("new", out var newId))
-            throw new YamlException(step.Start, step.End, "'rename-id' command missing 'new' parameter");
+        // Get the 'new' input
+        var newId = GetMapString(inputs, "new", variables) ??
+                    throw new YamlException(step.Start, step.End, "'rename-id' command missing 'new' input");
+
+        // Get the 'old' input
+        var oldId = GetMapString(inputs, "old", variables) ?? 
+                    throw new YamlException(step.Start, step.End, "'rename-id' command missing 'spdx' input");
 
         // Rename the ID
-        RenameId(spdxFile.ToString(), oldId.ToString(), newId.ToString());
+        RenameId(spdxFile, oldId, newId);
     }
 
     /// <summary>