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Implement variable assignment in pipelines #64

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Merged
yetanotherchris merged 1 commit into from
Jun 14, 2025
Merged

Implement variable assignment in pipelines #64

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124 changes: 101 additions & 23 deletions src/TextTemplate/TemplateEngine.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -132,6 +132,7 @@
private readonly IDictionary<string, object> _rootData;
private readonly object? _current;
private readonly object? _rootCurrent;
private bool _lastPipelineWasAssignment;
private static readonly Dictionary<string, Func<object?[], object?>> PipelineFuncs = new()
{
["lower"] = args => args.Length > 0 ? args[0]?.ToString()?.ToLowerInvariant() : null,
Expand All @@ -141,7 +142,7 @@
if (args.Length == 0) return string.Empty;
string fmt = args[0]?.ToString() ?? string.Empty;
var rest = args.Skip(1).ToArray();
return SprintfFormatter.Format(fmt, rest);

Check warning on line 145 in src/TextTemplate/TemplateEngine.cs

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Argument of type 'object?[]' cannot be used for parameter 'args' of type 'object[]' in 'string SprintfFormatter.Format(string format, params object[] args)' due to differences in the nullability of reference types.
},
["html"] = args => System.Net.WebUtility.HtmlEncode(string.Concat(args.Select(a => a?.ToString()))),
["js"] = args => System.Text.Encodings.Web.JavaScriptEncoder.Default.Encode(string.Concat(args.Select(a => a?.ToString()))),
Expand Down Expand Up @@ -173,7 +174,7 @@
}
if (current is IDictionary dict)
{
current = dict[key];

Check warning on line 177 in src/TextTemplate/TemplateEngine.cs

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Possible null reference argument for parameter 'key' in 'object? IDictionary.this[object key]'.
continue;
}
current = null;
Expand Down Expand Up @@ -282,13 +283,11 @@

public override string VisitPlaceholder(GoTextTemplateParser.PlaceholderContext context)
{
var commands = context.pipeline().command();
object? result = null;
bool first = true;
foreach (var cmd in commands)
object? result = EvaluatePipeline(context.pipeline());
if (_lastPipelineWasAssignment)
{
result = ExecuteCommand(cmd, first ? null : result);
first = false;
_lastPipelineWasAssignment = false;
return string.Empty;
}
return result?.ToString() ?? string.Empty;
}
Expand Down Expand Up @@ -342,7 +341,23 @@

public override string VisitRangeBlock(GoTextTemplateParser.RangeBlockContext context)
{
var sourceObj = ResolvePath(context.rangeClause().path());
object? sourceObj;
var clause = context.rangeClause();
var rcType = clause.GetType();
object? pipelineObj = rcType.GetMethod("pipeline")?.Invoke(clause, null);
if (clause.varList() != null && pipelineObj is GoTextTemplateParser.PipelineContext pc)
{
sourceObj = EvaluatePipeline(pc);
}
else
{
var pathCtx = rcType.GetMethod("path")?.Invoke(clause, null) as GoTextTemplateParser.PathContext;
if (pathCtx != null)
sourceObj = ResolvePath(pathCtx);
else
sourceObj = null;
}

if (sourceObj is not IEnumerable)
{
if (context.elseBlock() != null)
Expand Down Expand Up @@ -520,31 +535,44 @@

if (text.StartsWith("$"))
{
if (text == "$" || text == "$.")
return _rootCurrent;
text = text.StartsWith("$.") ? text.Substring(2) : text.Substring(1);
if (string.IsNullOrEmpty(text))
return _rootCurrent;
var segmentsRoot = ParseSegments(text);
object? currentRoot = _rootData;
foreach (var seg in segmentsRoot)
if (text == "$" || text.StartsWith("$."))
{
string rootText = text.StartsWith("$.") ? text.Substring(2) : string.Empty;
if (rootText.Length == 0)
return _rootCurrent;
var segRoot = ParseSegments(rootText);
object? curRoot = _rootData;
foreach (var seg in segRoot)
{
if (curRoot == null)
return null;
curRoot = ResolveSegment(curRoot, seg);
}
return curRoot;
}

var segmentsVar = ParseSegments(text);
if (segmentsVar.Count == 0 || segmentsVar[0] is not VariableName varSeg)
return null;
_data.TryGetValue(varSeg.Name, out object? current);
for (int idx = 1; idx < segmentsVar.Count; idx++)
{
if (currentRoot == null)
if (current == null)
return null;
currentRoot = ResolveSegment(currentRoot, seg);
current = ResolveSegment(current, segmentsVar[idx]);
}
return currentRoot;
return current;
}

var segments = ParseSegments(text);
object? current = _data;
object? currentDefault = _data;
foreach (var seg in segments)
{
if (current == null)
if (currentDefault == null)
return null;
current = ResolveSegment(current, seg);
currentDefault = ResolveSegment(currentDefault, seg);
}
return current;
return currentDefault;
}

private object? EvaluateExpr(GoTextTemplateParser.ExprContext context)
Expand Down Expand Up @@ -612,6 +640,22 @@

private object? EvaluatePipeline(GoTextTemplateParser.PipelineContext context)
{
_lastPipelineWasAssignment = false;

// Use reflection to support optional var assignment fields
GoTextTemplateParser.VarListContext? varList = null;
bool isColoneq = false;
bool isAssign = false;
var type = context.GetType();
var varListMethod = type.GetMethod("varList");
if (varListMethod != null)
varList = varListMethod.Invoke(context, null) as GoTextTemplateParser.VarListContext;
if (varList != null)
{
isColoneq = type.GetMethod("COLONEQ")?.Invoke(context, null) != null;
isAssign = type.GetMethod("ASSIGN")?.Invoke(context, null) != null;
}

var commands = context.command();
object? result = null;
bool first = true;
Expand All @@ -620,6 +664,25 @@
result = ExecuteCommand(cmd, first ? null : result);
first = false;
}

if (varList != null)
{
foreach (var v in varList.varName())
{
string name = v.GetText().TrimStart('$');
if (isAssign)
{
if (_data.ContainsKey(name))
_data[name] = result!;
}
else // COLONEQ
{
_data[name] = result!;
}
}
_lastPipelineWasAssignment = true;
}

return result;
}

Expand Down Expand Up @@ -718,11 +781,26 @@
public PathReference(string path) => Path = path;
}

private sealed class VariableName
{
public string Name { get; }
public VariableName(string name) => Name = name;
}

private static List<object> ParseSegments(string text)
{
var result = new List<object>();
int i = 0;
if (text.StartsWith(".")) i++;
if (text.StartsWith("$") && text.Length > 1 && text[1] != '.')
{
i = 1;
int start = i;
while (i < text.Length && (char.IsLetterOrDigit(text[i]) || text[i] == '_')) i++;
var varName = text.Substring(start, i - start);
result.Add(new VariableName(varName));
if (i < text.Length && text[i] == '.') i++;
}
else if (text.StartsWith(".")) i++;
while (i < text.Length)
{
if (text[i] == '.')
Expand Down
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