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Add stricter semicolon grammar, require() function, fix multi-rule xn

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To easily spot semicolon errors, they are now
mandatory delimiters after each construct.

Add require() to raise an error if a match is unsucessful.

Multiple rules in one xn files now possible.
This commit is contained in:
Dominic Höglinger 2026-04-25 01:08:54 +02:00
parent 0de7edee70
commit a05903df4d
5 changed files with 80 additions and 21 deletions
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32
Parser/XnParser.cs
View File

@ -199,11 +199,13 @@ namespace XNeedle.Parser
from ws1 in Parse.WhiteSpace.Many().Optional()
from open in Parse.Char('{')
from ws2 in Parse.WhiteSpace.Many().Optional()
from expressions in Parse.Ref(() => BangObject)
.Or(Parse.Ref(() => RuleObject))
.Or(ExprPart(ctx).Select(e => (Part)e))
.DelimitedBy(Parse.Char(';').Token())
from tailingsemi in Parse.Char(';').Optional()
from expressions in (
from expr in Parse.Ref(() => BangObject)
.Or(Parse.Ref(() => RuleObject))
.Or(ExprPart(ctx).Select(e => (Part)e))
from semi in Parse.Char(';').Token()
select expr
).Many()
from ws3 in Parse.WhiteSpace.Many().Optional()
from close in Parse.Char('}')
select new Bang{Name = new string([.. name]), Arguments = arguments, Body = expressions};
@ -214,15 +216,23 @@ namespace XNeedle.Parser
from ws1 in Parse.WhiteSpace.Many().Optional()
from open in Parse.Char('{')
from ws2 in Parse.WhiteSpace.Many().Optional()
from expressions in Parse.Ref(() => BangObject)
.Or(Parse.Ref(() => RuleObject))
.Or(ExprPart(ctx).Select(e => (Part)e))
.DelimitedBy(Parse.Char(';').Token())
from tailingsemi in Parse.Char(';').Optional()
from expressions in (
from expr in Parse.Ref(() => BangObject)
.Or(Parse.Ref(() => RuleObject))
.Or(ExprPart(ctx).Select(e => (Part)e))
from semi in Parse.Char(';').Token()
select expr
).Many()
from ws3 in Parse.WhiteSpace.Many().Optional()
from close in Parse.Char('}')
select new Rule{XPathSelector = selector, Body = expressions};
public static readonly Parser<IEnumerable<Part>> Rules =
(from rule in RuleObject.Token()
from semi in Parse.Char(';').Token()
select rule)
.Many()
.End();
static public string StripComments(string source)
{

25
Program.cs
View File

@ -40,10 +40,10 @@ namespace XNeedle
var rawSource = File.ReadAllText(opts.XnDefinition);
var xnSource = XnParser.StripComments(rawSource);
Rule masterRule;
IEnumerable<Part> rules;
try
{
masterRule = (Rule)XnParser.RuleObject.Parse(xnSource);
rules = XnParser.Rules.Parse(xnSource);
}
catch (ParseException ex)
{
@ -54,11 +54,19 @@ namespace XNeedle
if (showPosition)
{
Console.Error.WriteLine($"{opts.XnDefinition}({line},{col}): parse error: {ex.Message}");
var msg = ex.Message;
var hint = (msg.Contains("expected }") && !msg.Contains("expected ';'"))
? "Hint: a missing ';' terminator may be located just after this position"
: "";
Console.Error.WriteLine($"{opts.XnDefinition}({line},{col}): parse error: {msg}");
var srcLine = line <= lines.Length ? lines[line - 1].TrimEnd() : "";
var pointer = new string(' ', Math.Max(0, col - 1)) + "^";
Console.Error.WriteLine($" {srcLine}");
Console.Error.WriteLine($" {pointer}");
if (!string.IsNullOrEmpty(hint))
{
Console.Error.WriteLine($"\n{hint}");
}
}
else
{
@ -69,7 +77,16 @@ namespace XNeedle
var doc = XDocument.Load(opts.Input, LoadOptions.PreserveWhitespace);
var encoding = XmlRoundtripWriter.DetectEncoding(File.ReadAllBytes(opts.Input));
var sloc = new SourceLocation(opts.Input, encoding);
masterRule.Transform(doc, sloc);
try
{
foreach (var rule in rules.OfType<Rule>())
rule.Transform(doc, sloc);
}
catch (RequireException ex)
{
Console.Error.WriteLine($"{ex.SLoc.FilePath}({ex.SLoc.LineNumber}): require error: {ex.UserMessage}");
return;
}
using var writer = XmlRoundtripWriter.Create(opts.Input, opts.Output);
doc.WriteTo(writer);
Console.WriteLine($"Applied \"{opts.XnDefinition}\" to \"{opts.Input}\" and saved result to \"{opts.Output}\"");

13
Transformation/ContextFunctions.cs
View File

@ -187,5 +187,18 @@ namespace XNeedle.Transformation
}
return "";
}
public static string require(Context ctx, string message = "Required node not present")
{
if (ctx.Node == null)
{
throw new RequireException{SLoc=ctx.SLoc, UserMessage=message};
}
else
{
Console.WriteLine(ctx.Node.ToString());
}
return "";
}
}
}

15
Transformation/RequireException.cs Normal file
View File

@ -0,0 +1,15 @@
using System.Collections.Generic;
using System.Xml;
using System.Xml.Linq;
using System.Xml.XPath;
using XNeedle;
using XNeedle.Parser.Elements;
namespace XNeedle.Transformation
{
public class RequireException : Exception
{
public SourceLocation SLoc { get; set; }
public required string UserMessage { get; set; }
}
}

16
Transformation/Rule.cs
View File

@ -22,15 +22,19 @@ namespace XNeedle.Transformation
public override void Operate(Context ctx)
{
if(ctx.Node is null)
{
return;
}
var nodes = ctx.Node.XPathSelectElements(XPathSelector);
if(nodes is null)
var nodes = ctx.Node?.XPathSelectElements(XPathSelector);
if(nodes is null || nodes.Count() == 0)
{
var nullCtx = ctx.Clone();
nullCtx.Node = null;
nullCtx.SLoc = ctx.SLoc.WithLineNumber(-1);
foreach (var b in Body)
{
b.Operate(nullCtx);
}
return;
}
foreach (XElement n in nodes)
{
var loopCtx = ctx.Clone();