100 lines
3.5 KiB
C#
100 lines
3.5 KiB
C#
using System.Text.Json;
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namespace ScadaLink.SiteRuntime.Scripts;
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/// <summary>
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/// Read-only globals a trigger expression is compiled against. Exposes only
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/// attribute reads, backed by an in-memory snapshot — no I/O, no actor Ask,
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/// no side-effecting APIs. A missing attribute key reads as <c>null</c> and
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/// never throws.
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///
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/// Canonical attribute keys are dotted (e.g. "TempSensor.Reading"); the prefix
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/// logic here mirrors <see cref="AttributeAccessor.Resolve"/>.
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/// </summary>
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public sealed class TriggerExpressionGlobals
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{
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/// <summary>
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/// Extracts the <c>"expression"</c> field from an Expression-trigger config
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/// JSON document. Returns <c>null</c> for a missing, blank, or malformed
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/// config — the single parsing idiom shared by InstanceActor, ScriptActor,
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/// and AlarmActor.
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/// </summary>
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public static string? ExtractExpression(string? triggerConfigJson)
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{
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if (string.IsNullOrEmpty(triggerConfigJson)) return null;
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try
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{
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using var doc = JsonDocument.Parse(triggerConfigJson);
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var expr = doc.RootElement.TryGetProperty("expression", out var e)
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? e.GetString()
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: null;
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return string.IsNullOrWhiteSpace(expr) ? null : expr;
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}
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catch (JsonException)
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{
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return null;
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}
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}
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private readonly IReadOnlyDictionary<string, object?> _snapshot;
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public TriggerExpressionGlobals(IReadOnlyDictionary<string, object?> snapshot)
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=> _snapshot = snapshot;
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/// <summary>Attributes in the expression's own scope (root prefix).</summary>
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public ReadOnlyAttributes Attributes => new(_snapshot, "");
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/// <summary>Indexed access to child compositions' attributes.</summary>
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public ReadOnlyChildren Children => new(_snapshot);
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/// <summary>
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/// Parent composition (null at root). Set by the caller for derived/composed
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/// scopes; the runtime actors evaluate at root scope, so this stays null.
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/// </summary>
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public ReadOnlyComposition? Parent { get; init; }
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/// <summary>
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/// Read-only attribute view anchored at a canonical-name prefix. Indexing
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/// resolves to the canonical key ("" → key, "TempSensor" → "TempSensor.key").
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/// </summary>
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public sealed class ReadOnlyAttributes
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{
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private readonly IReadOnlyDictionary<string, object?> _s;
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private readonly string _prefix;
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public ReadOnlyAttributes(IReadOnlyDictionary<string, object?> s, string prefix)
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{
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_s = s;
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_prefix = prefix;
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}
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public object? this[string key] =>
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_s.TryGetValue(_prefix.Length == 0 ? key : _prefix + "." + key, out var v) ? v : null;
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}
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/// <summary>A read-only view of one composition at a canonical-name path.</summary>
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public sealed class ReadOnlyComposition
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{
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private readonly IReadOnlyDictionary<string, object?> _s;
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private readonly string _path;
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public ReadOnlyComposition(IReadOnlyDictionary<string, object?> s, string path)
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{
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_s = s;
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_path = path;
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}
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public ReadOnlyAttributes Attributes => new(_s, _path);
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}
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/// <summary>Dictionary-style accessor for child compositions.</summary>
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public sealed class ReadOnlyChildren
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{
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private readonly IReadOnlyDictionary<string, object?> _s;
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public ReadOnlyChildren(IReadOnlyDictionary<string, object?> s) => _s = s;
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public ReadOnlyComposition this[string compositionName] => new(_s, compositionName);
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}
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}
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