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A late-bound helper has priority over variable #353

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30 changes: 30 additions & 0 deletions source/Handlebars.Test/ComplexIntegrationTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -90,6 +90,36 @@ public void IfImplicitIteratorHelper()
Assert.Equal("<a href='http://google.com/'>Google</a><a href='http://yahoo.com/'>Yahoo!</a>", result);
}

// the helper has priority
// https://handlebarsjs.com/guide/expressions.html#disambiguating-helpers-calls-and-property-lookup
[Fact]
public void HelperWithSameNameVariable()
{
Handlebars.RegisterHelper("foo", (writer, context, arguments) =>
{
writer.Write("Helper");
});

var template = Handlebars.Compile("{{foo}}");
var result = template(new { foo = "Variable" });
Assert.Equal("Helper", result);
}

[Fact]
public void LateBoundHelperWithSameNameVariable()
{
var template = Handlebars.Compile("{{amoeba}}");

Assert.Equal("Variable", template(new { amoeba = "Variable" }));

Handlebars.RegisterHelper("amoeba", (writer, context, arguments) =>
{
writer.Write("Helper");
});

Assert.Equal("Helper", template(new { amoeba = "Variable" }));
}

[Fact]
public void BlockHelperWithSameNameVariable()
{
Expand Down
75 changes: 46 additions & 29 deletions source/Handlebars/Compiler/Translation/Expression/HelperFunctionBinder.cs
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Original file line number Diff line number Diff line change
@@ -1,8 +1,8 @@
using System;
using System.Linq;
using System.Linq.Expressions;
using System.Reflection;
using System.Collections.Generic;
using System.IO;

namespace HandlebarsDotNet.Compiler
{
Expand Down Expand Up @@ -32,27 +32,31 @@ protected override Expression VisitStatementExpression(StatementExpression sex)

protected override Expression VisitHelperExpression(HelperExpression hex)
{
if (CompilationContext.Configuration.Helpers.ContainsKey(hex.HelperName))
var arguments = new Expression[]
{
var helper = CompilationContext.Configuration.Helpers[hex.HelperName];
var arguments = new Expression[]
{
Expression.Property(
CompilationContext.BindingContext,
Expression.Property(
CompilationContext.BindingContext,
#if netstandard
typeof(BindingContext).GetRuntimeProperty("TextWriter")),
typeof(BindingContext).GetRuntimeProperty("TextWriter")
#else
typeof(BindingContext).GetProperty("TextWriter")),
typeof(BindingContext).GetProperty("TextWriter")
#endif
Expression.Property(
CompilationContext.BindingContext,
),
Expression.Property(
CompilationContext.BindingContext,
#if netstandard
typeof(BindingContext).GetRuntimeProperty("Value")),
typeof(BindingContext).GetRuntimeProperty("Value")
#else
typeof(BindingContext).GetProperty("Value")),
typeof(BindingContext).GetProperty("Value")
#endif
Expression.NewArrayInit(typeof(object), hex.Arguments.Select(a => Visit(a)))
};
),
Expression.Constant(hex.HelperName),
Expression.NewArrayInit(typeof(object), hex.Arguments.Select(a => Visit(a)))
};

if (CompilationContext.Configuration.Helpers.ContainsKey(hex.HelperName))
{
var helper = GetHelperWithName(CompilationContext.Configuration.Helpers[hex.HelperName]);
if (helper.Target != null)
{
return Expression.Call(
Expand Down Expand Up @@ -80,30 +84,43 @@ protected override Expression VisitHelperExpression(HelperExpression hex)
return Expression.Call(
Expression.Constant(this),
#if netstandard
new Action<BindingContext, string, IEnumerable<object>>(LateBindHelperExpression).GetMethodInfo(),
new HandlebarsHelperWithName(InvokeLateBindHelper).GetMethodInfo(),
#else
new Action<BindingContext, string, IEnumerable<object>>(LateBindHelperExpression).Method,
new HandlebarsHelperWithName(InvokeLateBindHelper).Method,
#endif
CompilationContext.BindingContext,
Expression.Constant(hex.HelperName),
Expression.NewArrayInit(typeof(object), hex.Arguments));
arguments);
}
}

private void LateBindHelperExpression(
BindingContext context,
private HandlebarsHelperWithName GetHelperWithName(HandlebarsHelper helper)
=> (writer, context, name, arguments) => helper(writer, context, arguments);

private void InvokeLateBindHelper(
TextWriter writer,
dynamic bindingContext,
string helperName,
IEnumerable<object> arguments)
{
if (!TryInvokeLateBoundHelper(CompilationContext, writer, bindingContext, helperName, arguments))
throw new HandlebarsRuntimeException(string.Format(
"Template references a helper that is not registered. Could not find helper '{0}'", helperName));
}

public static bool TryInvokeLateBoundHelper(
CompilationContext compilationContext,
TextWriter writer,
dynamic bindingContext,
string helperName,
IEnumerable<object> arguments)
{
if (CompilationContext.Configuration.Helpers.ContainsKey(helperName))
if (compilationContext.Configuration.Helpers.ContainsKey(helperName))
{
var helper = CompilationContext.Configuration.Helpers[helperName];
helper(context.TextWriter, context.Value, arguments.ToArray());
}
else
{
throw new HandlebarsRuntimeException(string.Format("Template references a helper that is not registered. Could not find helper '{0}'", helperName));
var helper = compilationContext.Configuration.Helpers[helperName];
helper(writer, bindingContext, arguments.ToArray());
return true;
}

return false;
}
}
}
41 changes: 23 additions & 18 deletions source/Handlebars/Compiler/Translation/Expression/PathBinder.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -27,23 +27,34 @@ protected override Expression VisitStatementExpression(StatementExpression sex)
{
if (sex.Body is PathExpression)
{
return Expression.Call(
Expression.Constant(this),
#if netstandard
var writeMethod = typeof(TextWriter).GetRuntimeMethod("Write", new [] { typeof(object) });
new Action<BindingContext, string>(WriteLateBoundHelperResultOrResolvedPath).GetMethodInfo(),
#else
var writeMethod = typeof(TextWriter).GetMethod("Write", new[] { typeof(object) });
new Action<BindingContext, string>(WriteLateBoundHelperResultOrResolvedPath).Method,
#endif
return Expression.Call(
Expression.Property(
CompilationContext.BindingContext,
"TextWriter"),
writeMethod, Visit(sex.Body));
CompilationContext.BindingContext,
Expression.Constant(((PathExpression) sex.Body).Path));
}
else
{
return Visit(sex.Body);
}
}

private void WriteLateBoundHelperResultOrResolvedPath(BindingContext bindingContext, string path)
{
var writer = bindingContext.TextWriter;

if (HelperFunctionBinder.TryInvokeLateBoundHelper(CompilationContext, writer, bindingContext, path, new object[] { }))
{
return;
}

writer.Write(ResolvePath(bindingContext, path));
}

protected override Expression VisitPathExpression(PathExpression pex)
{
return Expression.Call(
Expand Down Expand Up @@ -103,25 +114,19 @@ private object ResolvePath(BindingContext context, string path)
}

list[list.Count - 1] = list[list.Count - 1] + "." + next;
return list;
}
else
{
if (next.StartsWith("["))
if (next.StartsWith("[") && !next.EndsWith("]"))
{
insideEscapeBlock = true;
}

if (next.EndsWith("]"))
{
insideEscapeBlock = false;
}

list.Add(next);
return list;
}
return list;
});

foreach (var memberName in pathChain)
{
instance = ResolveValue(context, instance, memberName);
Expand Down Expand Up @@ -172,12 +177,12 @@ private object ResolveValue(BindingContext context, object instance, string segm
}

private static readonly Regex IndexRegex = new Regex(@"^\[?(?<index>\d+)\]?$", RegexOptions.None);

private object AccessMember(object instance, string memberName)
{
if (instance == null)
return new UndefinedBindingResult(memberName, CompilationContext.Configuration);

var resolvedMemberName = ResolveMemberName(instance, memberName);
var instanceType = instance.GetType();

Expand Down
30 changes: 16 additions & 14 deletions source/Handlebars/Compiler/Translation/Expression/SubExpressionVisitor.cs
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Original file line number Diff line number Diff line change
@@ -1,8 +1,8 @@
using System;
using System.Linq.Expressions;
using System.IO;
using System.Text;
using System.Reflection;
using System.Text;

namespace HandlebarsDotNet.Compiler
{
Expand All @@ -25,22 +25,23 @@ protected override Expression VisitSubExpression(SubExpressionExpression subex)
{
throw new HandlebarsCompilerException("Sub-expression does not contain a converted MethodCall expression");
}
HandlebarsHelper helper = GetHelperDelegateFromMethodCallExpression(helperCall);
HandlebarsHelperWithName helper = GetHelperDelegateFromMethodCallExpression(helperCall);
return Expression.Call(
#if netstandard
new Func<HandlebarsHelper, object, object[], string>(CaptureTextWriterOutputFromHelper).GetMethodInfo(),
new Func<HandlebarsHelperWithName, dynamic, string, object[], string>(CaptureTextWriterOutputFromHelper).GetMethodInfo(),
#else
new Func<HandlebarsHelper, object, object[], string>(CaptureTextWriterOutputFromHelper).Method,
new Func<HandlebarsHelperWithName, dynamic, string, object[], string>(CaptureTextWriterOutputFromHelper).Method,
#endif
Expression.Constant(helper),
Visit(helperCall.Arguments[1]),
Visit(helperCall.Arguments[2]));
Visit(helperCall.Arguments[2]),
Visit(helperCall.Arguments[3]));
}

private static HandlebarsHelper GetHelperDelegateFromMethodCallExpression(MethodCallExpression helperCall)
private static HandlebarsHelperWithName GetHelperDelegateFromMethodCallExpression(MethodCallExpression helperCall)
{
object target = helperCall.Object;
HandlebarsHelper helper;
HandlebarsHelperWithName helper;
if (target != null)
{
if (target is ConstantExpression)
Expand All @@ -52,31 +53,32 @@ private static HandlebarsHelper GetHelperDelegateFromMethodCallExpression(Method
throw new NotSupportedException("Helper method instance target must be reduced to a ConstantExpression");
}
#if netstandard
helper = (HandlebarsHelper)helperCall.Method.CreateDelegate(typeof(HandlebarsHelper), target);
helper = (HandlebarsHelperWithName)helperCall.Method.CreateDelegate(typeof(HandlebarsHelperWithName), target);
#else
helper = (HandlebarsHelper)Delegate.CreateDelegate(typeof(HandlebarsHelper), target, helperCall.Method);
helper = (HandlebarsHelperWithName)Delegate.CreateDelegate(typeof(HandlebarsHelperWithName), target, helperCall.Method);
#endif
}
else
{
#if netstandard
helper = (HandlebarsHelper)helperCall.Method.CreateDelegate(typeof(HandlebarsHelper));
helper = (HandlebarsHelperWithName)helperCall.Method.CreateDelegate(typeof(HandlebarsHelperWithName));
#else
helper = (HandlebarsHelper)Delegate.CreateDelegate(typeof(HandlebarsHelper), helperCall.Method);
helper = (HandlebarsHelperWithName)Delegate.CreateDelegate(typeof(HandlebarsHelperWithName), helperCall.Method);
#endif
}
return helper;
}

private static string CaptureTextWriterOutputFromHelper(
HandlebarsHelper helper,
object context,
HandlebarsHelperWithName helper,
dynamic context,
string name,
object[] arguments)
{
var builder = new StringBuilder();
using (var writer = new StringWriter(builder))
{
helper(writer, context, arguments);
helper(writer, context, name, arguments);
}
return builder.ToString();
}
Expand Down
3 changes: 3 additions & 0 deletions source/Handlebars/Handlebars.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,9 @@ namespace HandlebarsDotNet
public delegate void HandlebarsHelper(TextWriter output, dynamic context, params object[] arguments);
public delegate void HandlebarsBlockHelper(TextWriter output, HelperOptions options, dynamic context, params object[] arguments);

// a HandlebarsHelper that also stores the name of the helper for later use
internal delegate void HandlebarsHelperWithName(TextWriter output, dynamic context, string name, params object[] arguments);

public sealed partial class Handlebars
{
// Lazy-load Handlebars environment to ensure thread safety. See Jon Skeet's excellent article on this for more info. http://csharpindepth.com/Articles/General/Singleton.aspx
Expand Down