GitHub Actions Runner

src/Runner.Worker/ActionManifestManager.cs

@@ -0,0 +1,980 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Threading;
+using GitHub.Runner.Common;
+using GitHub.Runner.Sdk;
+using System.Reflection;
+using GitHub.DistributedTask.Pipelines.ObjectTemplating;
+using GitHub.DistributedTask.ObjectTemplating.Schema;
+using GitHub.DistributedTask.ObjectTemplating;
+using GitHub.DistributedTask.ObjectTemplating.Tokens;
+using GitHub.DistributedTask.Pipelines.ContextData;
+using YamlDotNet.Core;
+using YamlDotNet.Core.Events;
+using System.Globalization;
+using System.Linq;
+
+namespace GitHub.Runner.Worker
+{
+    [ServiceLocator(Default = typeof(ActionManifestManager))]
+    public interface IActionManifestManager : IRunnerService
+    {
+        ActionDefinitionData Load(IExecutionContext executionContext, string manifestFile);
+
+        List<string> EvaluateContainerArguments(IExecutionContext executionContext, SequenceToken token, IDictionary<string, PipelineContextData> contextData);
+
+        Dictionary<string, string> EvaluateContainerEnvironment(IExecutionContext executionContext, MappingToken token, IDictionary<string, PipelineContextData> contextData);
+
+        string EvaluateDefaultInput(IExecutionContext executionContext, string inputName, TemplateToken token, IDictionary<string, PipelineContextData> contextData);
+    }
+
+    public sealed class ActionManifestManager : RunnerService, IActionManifestManager
+    {
+        private TemplateSchema _actionManifestSchema;
+
+        public override void Initialize(IHostContext hostContext)
+        {
+            base.Initialize(hostContext);
+
+            var assembly = Assembly.GetExecutingAssembly();
+            var json = default(string);
+            using (var stream = assembly.GetManifestResourceStream("GitHub.Runner.Worker.action_yaml.json"))
+            using (var streamReader = new StreamReader(stream))
+            {
+                json = streamReader.ReadToEnd();
+            }
+
+            var objectReader = new JsonObjectReader(null, json);
+            _actionManifestSchema = TemplateSchema.Load(objectReader);
+            ArgUtil.NotNull(_actionManifestSchema, nameof(_actionManifestSchema));
+            Trace.Info($"Load schema file with definitions: {StringUtil.ConvertToJson(_actionManifestSchema.Definitions.Keys)}");
+        }
+
+        public ActionDefinitionData Load(IExecutionContext executionContext, string manifestFile)
+        {
+            var context = CreateContext(executionContext, null);
+            ActionDefinitionData actionDefinition = new ActionDefinitionData();
+            try
+            {
+                var token = default(TemplateToken);
+
+                // Get the file ID
+                var fileId = context.GetFileId(manifestFile);
+                var fileContent = File.ReadAllText(manifestFile);
+                using (var stringReader = new StringReader(fileContent))
+                {
+                    var yamlObjectReader = new YamlObjectReader(null, stringReader);
+                    token = TemplateReader.Read(context, "action-root", yamlObjectReader, fileId, out _);
+                }
+
+                var actionMapping = token.AssertMapping("action manifest root");
+                foreach (var actionPair in actionMapping)
+                {
+                    var propertyName = actionPair.Key.AssertString($"action.yml property key");
+
+                    switch (propertyName.Value)
+                    {
+                        case "name":
+                            actionDefinition.Name = actionPair.Value.AssertString("name").Value;
+                            break;
+
+                        case "description":
+                            actionDefinition.Description = actionPair.Value.AssertString("description").Value;
+                            break;
+
+                        case "inputs":
+                            ConvertInputs(context, actionPair.Value, actionDefinition);
+                            break;
+
+                        case "runs":
+                            actionDefinition.Execution = ConvertRuns(context, actionPair.Value);
+                            break;
+                        default:
+                            Trace.Info($"Ignore action property {propertyName}.");
+                            break;
+                    }
+                }
+            }
+            catch (Exception ex)
+            {
+                Trace.Error(ex);
+                context.Errors.Add(ex);
+            }
+
+            if (context.Errors.Count > 0)
+            {
+                foreach (var error in context.Errors)
+                {
+                    Trace.Error($"Action.yml load error: {error.Message}");
+                    executionContext.Error(error.Message);
+                }
+
+                throw new ArgumentException($"Fail to load {manifestFile}");
+            }
+
+            if (actionDefinition.Execution == null)
+            {
+                executionContext.Debug($"Loaded action.yml file: {StringUtil.ConvertToJson(actionDefinition)}");
+                throw new ArgumentException($"Top level 'run:' section is required for {manifestFile}");
+            }
+            else
+            {
+                Trace.Info($"Loaded action.yml file: {StringUtil.ConvertToJson(actionDefinition)}");
+            }
+
+            return actionDefinition;
+        }
+
+        public List<string> EvaluateContainerArguments(
+            IExecutionContext executionContext,
+            SequenceToken token,
+            IDictionary<string, PipelineContextData> contextData)
+        {
+            var result = new List<string>();
+
+            if (token != null)
+            {
+                var context = CreateContext(executionContext, contextData);
+                try
+                {
+                    var evaluateResult = TemplateEvaluator.Evaluate(context, "container-runs-args", token, 0, null, omitHeader: true);
+                    context.Errors.Check();
+
+                    Trace.Info($"Arguments evaluate result: {StringUtil.ConvertToJson(evaluateResult)}");
+
+                    // Sequence
+                    var args = evaluateResult.AssertSequence("container args");
+
+                    foreach (var arg in args)
+                    {
+                        var str = arg.AssertString("container arg").Value;
+                        result.Add(str);
+                        Trace.Info($"Add argument {str}");
+                    }
+                }
+                catch (Exception ex) when (!(ex is TemplateValidationException))
+                {
+                    Trace.Error(ex);
+                    context.Errors.Add(ex);
+                }
+
+                context.Errors.Check();
+            }
+
+            return result;
+        }
+
+        public Dictionary<string, string> EvaluateContainerEnvironment(
+            IExecutionContext executionContext,
+            MappingToken token,
+            IDictionary<string, PipelineContextData> contextData)
+        {
+            var result = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
+
+            if (token != null)
+            {
+                var context = CreateContext(executionContext, contextData);
+                try
+                {
+                    var evaluateResult = TemplateEvaluator.Evaluate(context, "container-runs-env", token, 0, null, omitHeader: true);
+                    context.Errors.Check();
+
+                    Trace.Info($"Environments evaluate result: {StringUtil.ConvertToJson(evaluateResult)}");
+
+                    // Mapping
+                    var mapping = evaluateResult.AssertMapping("container env");
+
+                    foreach (var pair in mapping)
+                    {
+                        // Literal key
+                        var key = pair.Key.AssertString("container env key");
+
+                        // Literal value
+                        var value = pair.Value.AssertString("container env value");
+                        result[key.Value] = value.Value;
+
+                        Trace.Info($"Add env {key} = {value}");
+                    }
+                }
+                catch (Exception ex) when (!(ex is TemplateValidationException))
+                {
+                    Trace.Error(ex);
+                    context.Errors.Add(ex);
+                }
+
+                context.Errors.Check();
+            }
+
+            return result;
+        }
+
+        public string EvaluateDefaultInput(
+            IExecutionContext executionContext,
+            string inputName,
+            TemplateToken token,
+            IDictionary<string, PipelineContextData> contextData)
+        {
+            string result = "";
+            if (token != null)
+            {
+                var context = CreateContext(executionContext, contextData);
+                try
+                {
+                    var evaluateResult = TemplateEvaluator.Evaluate(context, "input-default-context", token, 0, null, omitHeader: true);
+                    context.Errors.Check();
+
+                    Trace.Info($"Input '{inputName}': default value evaluate result: {StringUtil.ConvertToJson(evaluateResult)}");
+
+                    // String
+                    result = evaluateResult.AssertString($"default value for input '{inputName}'").Value;
+                }
+                catch (Exception ex) when (!(ex is TemplateValidationException))
+                {
+                    Trace.Error(ex);
+                    context.Errors.Add(ex);
+                }
+
+                context.Errors.Check();
+            }
+
+            return result;
+        }
+
+        private TemplateContext CreateContext(
+            IExecutionContext executionContext,
+            IDictionary<string, PipelineContextData> contextData)
+        {
+            var result = new TemplateContext
+            {
+                CancellationToken = CancellationToken.None,
+                Errors = new TemplateValidationErrors(10, 500),
+                Memory = new TemplateMemory(
+                    maxDepth: 100,
+                    maxEvents: 1000000,
+                    maxBytes: 10 * 1024 * 1024),
+                Schema = _actionManifestSchema,
+                TraceWriter = executionContext.ToTemplateTraceWriter(),
+            };
+
+            if (contextData?.Count > 0)
+            {
+                foreach (var pair in contextData)
+                {
+                    result.ExpressionValues[pair.Key] = pair.Value;
+                }
+            }
+
+            return result;
+        }
+
+        private ActionExecutionData ConvertRuns(
+            TemplateContext context,
+            TemplateToken inputsToken)
+        {
+            var runsMapping = inputsToken.AssertMapping("runs");
+            var usingToken = default(StringToken);
+            var imageToken = default(StringToken);
+            var argsToken = default(SequenceToken);
+            var entrypointToken = default(StringToken);
+            var envToken = default(MappingToken);
+            var mainToken = default(StringToken);
+            var pluginToken = default(StringToken);
+            var postToken = default(StringToken);
+            var postEntrypointToken = default(StringToken);
+            var postIfToken = default(StringToken);
+            foreach (var run in runsMapping)
+            {
+                var runsKey = run.Key.AssertString("runs key").Value;
+                switch (runsKey)
+                {
+                    case "using":
+                        usingToken = run.Value.AssertString("using");
+                        break;
+                    case "image":
+                        imageToken = run.Value.AssertString("image");
+                        break;
+                    case "args":
+                        argsToken = run.Value.AssertSequence("args");
+                        break;
+                    case "entrypoint":
+                        entrypointToken = run.Value.AssertString("entrypoint");
+                        break;
+                    case "env":
+                        envToken = run.Value.AssertMapping("env");
+                        break;
+                    case "main":
+                        mainToken = run.Value.AssertString("main");
+                        break;
+                    case "plugin":
+                        pluginToken = run.Value.AssertString("plugin");
+                        break;
+                    case "post":
+                        postToken = run.Value.AssertString("post");
+                        break;
+                    case "post-entrypoint":
+                        postEntrypointToken = run.Value.AssertString("post-entrypoint");
+                        break;
+                    case "post-if":
+                        postIfToken = run.Value.AssertString("post-if");
+                        break;
+                    default:
+                        Trace.Info($"Ignore run property {runsKey}.");
+                        break;
+                }
+            }
+
+            if (usingToken != null)
+            {
+                if (string.Equals(usingToken.Value, "docker", StringComparison.OrdinalIgnoreCase))
+                {
+                    if (string.IsNullOrEmpty(imageToken?.Value))
+                    {
+                        throw new ArgumentNullException($"Image is not provided.");
+                    }
+                    else
+                    {
+                        return new ContainerActionExecutionData()
+                        {
+                            Image = imageToken.Value,
+                            Arguments = argsToken,
+                            EntryPoint = entrypointToken?.Value,
+                            Environment = envToken,
+                            Cleanup = postEntrypointToken?.Value,
+                            CleanupCondition = postIfToken?.Value
+                        };
+                    }
+                }
+                else if (string.Equals(usingToken.Value, "node12", StringComparison.OrdinalIgnoreCase))
+                {
+                    if (string.IsNullOrEmpty(mainToken?.Value))
+                    {
+                        throw new ArgumentNullException($"Entry javascript fils is not provided.");
+                    }
+                    else
+                    {
+                        return new NodeJSActionExecutionData()
+                        {
+                            Script = mainToken.Value,
+                            Cleanup = postToken?.Value,
+                            CleanupCondition = postIfToken?.Value
+                        };
+                    }
+                }
+                else
+                {
+                    throw new ArgumentOutOfRangeException($"'using: {usingToken.Value}' is not supported, use 'docker' or 'node12' instead.");
+                }
+            }
+            else if (pluginToken != null)
+            {
+                return new PluginActionExecutionData()
+                {
+                    Plugin = pluginToken.Value
+                };
+            }
+
+            throw new NotSupportedException(nameof(ConvertRuns));
+        }
+
+        private void ConvertInputs(
+            TemplateContext context,
+            TemplateToken inputsToken,
+            ActionDefinitionData actionDefinition)
+        {
+            actionDefinition.Inputs = new MappingToken(null, null, null);
+            var inputsMapping = inputsToken.AssertMapping("inputs");
+            foreach (var input in inputsMapping)
+            {
+                bool hasDefault = false;
+                var inputName = input.Key.AssertString("input name");
+                var inputMetadata = input.Value.AssertMapping("input metadata");
+                foreach (var metadata in inputMetadata)
+                {
+                    var metadataName = metadata.Key.AssertString("input metadata").Value;
+                    if (string.Equals(metadataName, "default", StringComparison.OrdinalIgnoreCase))
+                    {
+                        hasDefault = true;
+                        actionDefinition.Inputs.Add(inputName, metadata.Value);
+                    }
+                    else if (string.Equals(metadataName, "deprecationMessage", StringComparison.OrdinalIgnoreCase))
+                    {
+                        if (actionDefinition.Deprecated == null)
+                        {
+                            actionDefinition.Deprecated = new Dictionary<String, String>();
+                        }
+                        var message = metadata.Value.AssertString("input deprecationMessage");
+                        actionDefinition.Deprecated.Add(inputName.Value, message.Value);
+                    }
+                }
+
+                if (!hasDefault)
+                {
+                    actionDefinition.Inputs.Add(inputName, new StringToken(null, null, null, string.Empty));
+                }
+            }
+        }
+    }
+
+    /// <summary>
+    /// Converts a YAML file into a TemplateToken
+    /// </summary>
+    internal sealed class YamlObjectReader : IObjectReader
+    {
+        internal YamlObjectReader(
+            Int32? fileId,
+            TextReader input)
+        {
+            m_fileId = fileId;
+            m_parser = new Parser(input);
+        }
+
+        public Boolean AllowLiteral(out LiteralToken value)
+        {
+            if (EvaluateCurrent() is Scalar scalar)
+            {
+                // Tag specified
+                if (!string.IsNullOrEmpty(scalar.Tag))
+                {
+                    // String tag
+                    if (string.Equals(scalar.Tag, c_stringTag, StringComparison.Ordinal))
+                    {
+                        value = new StringToken(m_fileId, scalar.Start.Line, scalar.Start.Column, scalar.Value);
+                        MoveNext();
+                        return true;
+                    }
+
+                    // Not plain style
+                    if (scalar.Style != ScalarStyle.Plain)
+                    {
+                        throw new NotSupportedException($"The scalar style '{scalar.Style}' on line {scalar.Start.Line} and column {scalar.Start.Column} is not valid with the tag '{scalar.Tag}'");
+                    }
+
+                    // Boolean, Float, Integer, or Null
+                    switch (scalar.Tag)
+                    {
+                        case c_booleanTag:
+                            value = ParseBoolean(scalar);
+                            break;
+                        case c_floatTag:
+                            value = ParseFloat(scalar);
+                            break;
+                        case c_integerTag:
+                            value = ParseInteger(scalar);
+                            break;
+                        case c_nullTag:
+                            value = ParseNull(scalar);
+                            break;
+                        default:
+                            throw new NotSupportedException($"Unexpected tag '{scalar.Tag}'");
+                    }
+
+                    MoveNext();
+                    return true;
+                }
+
+                // Plain style, determine type using YAML 1.2 "core" schema https://yaml.org/spec/1.2/spec.html#id2804923
+                if (scalar.Style == ScalarStyle.Plain)
+                {
+                    if (MatchNull(scalar, out var nullToken))
+                    {
+                        value = nullToken;
+                    }
+                    else if (MatchBoolean(scalar, out var booleanToken))
+                    {
+                        value = booleanToken;
+                    }
+                    else if (MatchInteger(scalar, out var numberToken) ||
+                        MatchFloat(scalar, out numberToken))
+                    {
+                        value = numberToken;
+                    }
+                    else
+                    {
+                        value = new StringToken(m_fileId, scalar.Start.Line, scalar.Start.Column, scalar.Value);
+                    }
+
+                    MoveNext();
+                    return true;
+                }
+
+                // Otherwise assume string
+                value = new StringToken(m_fileId, scalar.Start.Line, scalar.Start.Column, scalar.Value);
+                MoveNext();
+                return true;
+            }
+
+            value = default;
+            return false;
+        }
+
+        public Boolean AllowSequenceStart(out SequenceToken value)
+        {
+            if (EvaluateCurrent() is SequenceStart sequenceStart)
+            {
+                value = new SequenceToken(m_fileId, sequenceStart.Start.Line, sequenceStart.Start.Column);
+                MoveNext();
+                return true;
+            }
+
+            value = default;
+            return false;
+        }
+
+        public Boolean AllowSequenceEnd()
+        {
+            if (EvaluateCurrent() is SequenceEnd)
+            {
+                MoveNext();
+                return true;
+            }
+
+            return false;
+        }
+
+        public Boolean AllowMappingStart(out MappingToken value)
+        {
+            if (EvaluateCurrent() is MappingStart mappingStart)
+            {
+                value = new MappingToken(m_fileId, mappingStart.Start.Line, mappingStart.Start.Column);
+                MoveNext();
+                return true;
+            }
+
+            value = default;
+            return false;
+        }
+
+        public Boolean AllowMappingEnd()
+        {
+            if (EvaluateCurrent() is MappingEnd)
+            {
+                MoveNext();
+                return true;
+            }
+
+            return false;
+        }
+
+        /// <summary>
+        /// Consumes the last parsing events, which are expected to be DocumentEnd and StreamEnd.
+        /// </summary>
+        public void ValidateEnd()
+        {
+            if (EvaluateCurrent() is DocumentEnd)
+            {
+                MoveNext();
+            }
+            else
+            {
+                throw new InvalidOperationException("Expected document end parse event");
+            }
+
+            if (EvaluateCurrent() is StreamEnd)
+            {
+                MoveNext();
+            }
+            else
+            {
+                throw new InvalidOperationException("Expected stream end parse event");
+            }
+
+            if (MoveNext())
+            {
+                throw new InvalidOperationException("Expected end of parse events");
+            }
+        }
+
+        /// <summary>
+        /// Consumes the first parsing events, which are expected to be StreamStart and DocumentStart.
+        /// </summary>
+        public void ValidateStart()
+        {
+            if (EvaluateCurrent() != null)
+            {
+                throw new InvalidOperationException("Unexpected parser state");
+            }
+
+            if (!MoveNext())
+            {
+                throw new InvalidOperationException("Expected a parse event");
+            }
+
+            if (EvaluateCurrent() is StreamStart)
+            {
+                MoveNext();
+            }
+            else
+            {
+                throw new InvalidOperationException("Expected stream start parse event");
+            }
+
+            if (EvaluateCurrent() is DocumentStart)
+            {
+                MoveNext();
+            }
+            else
+            {
+                throw new InvalidOperationException("Expected document start parse event");
+            }
+        }
+
+        private ParsingEvent EvaluateCurrent()
+        {
+            if (m_current == null)
+            {
+                m_current = m_parser.Current;
+                if (m_current != null)
+                {
+                    if (m_current is Scalar scalar)
+                    {
+                        // Verify not using achors
+                        if (scalar.Anchor != null)
+                        {
+                            throw new InvalidOperationException($"Anchors are not currently supported. Remove the anchor '{scalar.Anchor}'");
+                        }
+                    }
+                    else if (m_current is MappingStart mappingStart)
+                    {
+                        // Verify not using achors
+                        if (mappingStart.Anchor != null)
+                        {
+                            throw new InvalidOperationException($"Anchors are not currently supported. Remove the anchor '{mappingStart.Anchor}'");
+                        }
+                    }
+                    else if (m_current is SequenceStart sequenceStart)
+                    {
+                        // Verify not using achors
+                        if (sequenceStart.Anchor != null)
+                        {
+                            throw new InvalidOperationException($"Anchors are not currently supported. Remove the anchor '{sequenceStart.Anchor}'");
+                        }
+                    }
+                    else if (!(m_current is MappingEnd) &&
+                        !(m_current is SequenceEnd) &&
+                        !(m_current is DocumentStart) &&
+                        !(m_current is DocumentEnd) &&
+                        !(m_current is StreamStart) &&
+                        !(m_current is StreamEnd))
+                    {
+                        throw new InvalidOperationException($"Unexpected parsing event type: {m_current.GetType().Name}");
+                    }
+                }
+            }
+
+            return m_current;
+        }
+
+        private Boolean MoveNext()
+        {
+            m_current = null;
+            return m_parser.MoveNext();
+        }
+
+        private BooleanToken ParseBoolean(Scalar scalar)
+        {
+            if (MatchBoolean(scalar, out var token))
+            {
+                return token;
+            }
+
+            ThrowInvalidValue(scalar, c_booleanTag); // throws
+            return default;
+        }
+
+        private NumberToken ParseFloat(Scalar scalar)
+        {
+            if (MatchFloat(scalar, out var token))
+            {
+                return token;
+            }
+
+            ThrowInvalidValue(scalar, c_floatTag); // throws
+            return default;
+        }
+
+        private NumberToken ParseInteger(Scalar scalar)
+        {
+            if (MatchInteger(scalar, out var token))
+            {
+                return token;
+            }
+
+            ThrowInvalidValue(scalar, c_integerTag); // throws
+            return default;
+        }
+
+        private NullToken ParseNull(Scalar scalar)
+        {
+            if (MatchNull(scalar, out var token))
+            {
+                return token;
+            }
+
+            ThrowInvalidValue(scalar, c_nullTag); // throws
+            return default;
+        }
+
+        private Boolean MatchBoolean(
+            Scalar scalar,
+            out BooleanToken value)
+        {
+            // YAML 1.2 "core" schema https://yaml.org/spec/1.2/spec.html#id2804923
+            switch (scalar.Value ?? string.Empty)
+            {
+                case "true":
+                case "True":
+                case "TRUE":
+                    value = new BooleanToken(m_fileId, scalar.Start.Line, scalar.Start.Column, true);
+                    return true;
+                case "false":
+                case "False":
+                case "FALSE":
+                    value = new BooleanToken(m_fileId, scalar.Start.Line, scalar.Start.Column, false);
+                    return true;
+            }
+
+            value = default;
+            return false;
+        }
+
+        private Boolean MatchFloat(
+            Scalar scalar,
+            out NumberToken value)
+        {
+            // YAML 1.2 "core" schema https://yaml.org/spec/1.2/spec.html#id2804923
+            var str = scalar.Value;
+            if (!string.IsNullOrEmpty(str))
+            {
+                // Check for [-+]?(\.inf|\.Inf|\.INF)|\.nan|\.NaN|\.NAN
+                switch (str)
+                {
+                    case ".inf":
+                    case ".Inf":
+                    case ".INF":
+                    case "+.inf":
+                    case "+.Inf":
+                    case "+.INF":
+                        value = new NumberToken(m_fileId, scalar.Start.Line, scalar.Start.Column, Double.PositiveInfinity);
+                        return true;
+                    case "-.inf":
+                    case "-.Inf":
+                    case "-.INF":
+                        value = new NumberToken(m_fileId, scalar.Start.Line, scalar.Start.Column, Double.NegativeInfinity);
+                        return true;
+                    case ".nan":
+                    case ".NaN":
+                    case ".NAN":
+                        value = new NumberToken(m_fileId, scalar.Start.Line, scalar.Start.Column, Double.NaN);
+                        return true;
+                }
+
+                // Otherwise check [-+]?(\.[0-9]+|[0-9]+(\.[0-9]*)?)([eE][-+]?[0-9]+)?
+
+                // Skip leading sign
+                var index = str[0] == '-' || str[0] == '+' ? 1 : 0;
+
+                // Check for integer portion
+                var length = str.Length;
+                var hasInteger = false;
+                while (index < length && str[index] >= '0' && str[index] <= '9')
+                {
+                    hasInteger = true;
+                    index++;
+                }
+
+                // Check for decimal point
+                var hasDot = false;
+                if (index < length && str[index] == '.')
+                {
+                    hasDot = true;
+                    index++;
+                }
+
+                // Check for decimal portion
+                var hasDecimal = false;
+                while (index < length && str[index] >= '0' && str[index] <= '9')
+                {
+                    hasDecimal = true;
+                    index++;
+                }
+
+                // Check [-+]?(\.[0-9]+|[0-9]+(\.[0-9]*)?)
+                if ((hasDot && hasDecimal) || hasInteger)
+                {
+                    // Check for end
+                    if (index == length)
+                    {
+                        // Try parse
+                        if (Double.TryParse(str, NumberStyles.AllowLeadingSign | NumberStyles.AllowDecimalPoint, CultureInfo.InvariantCulture, out var doubleValue))
+                        {
+                            value = new NumberToken(m_fileId, scalar.Start.Line, scalar.Start.Column, doubleValue);
+                            return true;
+                        }
+                        // Otherwise exceeds range
+                        else
+                        {
+                            ThrowInvalidValue(scalar, c_floatTag); // throws
+                        }
+                    }
+                    // Check [eE][-+]?[0-9]
+                    else if (index < length && (str[index] == 'e' || str[index] == 'E'))
+                    {
+                        index++;
+
+                        // Skip sign
+                        if (index < length && (str[index] == '-' || str[index] == '+'))
+                        {
+                            index++;
+                        }
+
+                        // Check for exponent
+                        var hasExponent = false;
+                        while (index < length && str[index] >= '0' && str[index] <= '9')
+                        {
+                            hasExponent = true;
+                            index++;
+                        }
+
+                        // Check for end
+                        if (hasExponent && index == length)
+                        {
+                            // Try parse
+                            if (Double.TryParse(str, NumberStyles.AllowLeadingSign | NumberStyles.AllowDecimalPoint | NumberStyles.AllowExponent, CultureInfo.InvariantCulture, out var doubleValue))
+                            {
+                                value = new NumberToken(m_fileId, scalar.Start.Line, scalar.Start.Column, (Double)doubleValue);
+                                return true;
+                            }
+                            // Otherwise exceeds range
+                            else
+                            {
+                                ThrowInvalidValue(scalar, c_floatTag); // throws
+                            }
+                        }
+                    }
+                }
+            }
+
+            value = default;
+            return false;
+        }
+
+        private Boolean MatchInteger(
+            Scalar scalar,
+            out NumberToken value)
+        {
+            // YAML 1.2 "core" schema https://yaml.org/spec/1.2/spec.html#id2804923
+            var str = scalar.Value;
+            if (!string.IsNullOrEmpty(str))
+            {
+                // Check for [0-9]+
+                var firstChar = str[0];
+                if (firstChar >= '0' && firstChar <= '9' &&
+                    str.Skip(1).All(x => x >= '0' && x <= '9'))
+                {
+                    // Try parse
+                    if (Double.TryParse(str, NumberStyles.None, CultureInfo.InvariantCulture, out var doubleValue))
+                    {
+                        value = new NumberToken(m_fileId, scalar.Start.Line, scalar.Start.Column, doubleValue);
+                        return true;
+                    }
+
+                    // Otherwise exceeds range
+                    ThrowInvalidValue(scalar, c_integerTag); // throws
+                }
+                // Check for (-|+)[0-9]+
+                else if ((firstChar == '-' || firstChar == '+') &&
+                    str.Length > 1 &&
+                    str.Skip(1).All(x => x >= '0' && x <= '9'))
+                {
+                    // Try parse
+                    if (Double.TryParse(str, NumberStyles.AllowLeadingSign, CultureInfo.InvariantCulture, out var doubleValue))
+                    {
+                        value = new NumberToken(m_fileId, scalar.Start.Line, scalar.Start.Column, doubleValue);
+                        return true;
+                    }
+
+                    // Otherwise exceeds range
+                    ThrowInvalidValue(scalar, c_integerTag); // throws
+                }
+                // Check for 0x[0-9a-fA-F]+
+                else if (firstChar == '0' &&
+                    str.Length > 2 &&
+                    str[1] == 'x' &&
+                    str.Skip(2).All(x => (x >= '0' && x <= '9') || (x >= 'a' && x <= 'f') || (x >= 'A' && x <= 'F')))
+                {
+                    // Try parse
+                    if (Int32.TryParse(str.Substring(2), NumberStyles.AllowHexSpecifier, CultureInfo.InvariantCulture, out var integerValue))
+                    {
+                        value = new NumberToken(m_fileId, scalar.Start.Line, scalar.Start.Column, integerValue);
+                        return true;
+                    }
+
+                    // Otherwise exceeds range
+                    ThrowInvalidValue(scalar, c_integerTag); // throws
+                }
+                // Check for 0o[0-9]+
+                else if (firstChar == '0' &&
+                    str.Length > 2 &&
+                    str[1] == 'o' &&
+                    str.Skip(2).All(x => x >= '0' && x <= '7'))
+                {
+                    // Try parse
+                    var integerValue = default(Int32);
+                    try
+                    {
+                        integerValue = Convert.ToInt32(str.Substring(2), 8);
+                    }
+                    // Otherwise exceeds range
+                    catch (Exception)
+                    {
+                        ThrowInvalidValue(scalar, c_integerTag); // throws
+                    }
+
+                    value = new NumberToken(m_fileId, scalar.Start.Line, scalar.Start.Column, integerValue);
+                    return true;
+                }
+            }
+
+            value = default;
+            return false;
+        }
+
+        private Boolean MatchNull(
+            Scalar scalar,
+            out NullToken value)
+        {
+            // YAML 1.2 "core" schema https://yaml.org/spec/1.2/spec.html#id2804923
+            switch (scalar.Value ?? string.Empty)
+            {
+                case "":
+                case "null":
+                case "Null":
+                case "NULL":
+                case "~":
+                    value = new NullToken(m_fileId, scalar.Start.Line, scalar.Start.Column);
+                    return true;
+            }
+
+            value = default;
+            return false;
+        }
+
+        private void ThrowInvalidValue(
+            Scalar scalar,
+            String tag)
+        {
+            throw new NotSupportedException($"The value '{scalar.Value}' on line {scalar.Start.Line} and column {scalar.Start.Column} is invalid for the type '{scalar.Tag}'");
+        }
+
+        private const String c_booleanTag = "tag:yaml.org,2002:bool";
+        private const String c_floatTag = "tag:yaml.org,2002:float";
+        private const String c_integerTag = "tag:yaml.org,2002:int";
+        private const String c_nullTag = "tag:yaml.org,2002:null";
+        private const String c_stringTag = "tag:yaml.org,2002:string";
+        private readonly Int32? m_fileId;
+        private readonly Parser m_parser;
+        private ParsingEvent m_current;
+    }
+}
+