ExcelReportLib

A .NET 8 library for generating .xlsx workbooks from a custom XML DSL (urn:excelreport:v1) and runtime data.

Overview

ExcelReportLib converts declarative report definitions into Excel files through a staged pipeline:

1. Parse XML DSL into AST nodes.
2. Evaluate expressions and resolve styles/components.
3. Expand layout primitives (grid, repeat, use, cell) into concrete coordinates.
4. Build worksheet state (cells, merges, named areas, sheet options).
5. Render OpenXML workbook streams, including _Issues and _Audit sheets when applicable.

Primary orchestration is handled by ReportGenerator.

Features

• XML DSL-based report definitions (urn:excelreport:v1)
• Expression evaluation (@(root...), @(data...), @(vars...))
• Reusable components via <component> and <use>
• External component import via <componentImport>
• Collection expansion via <repeat>
• Style system with imports, composition, borders, and number formats
• Named areas and formula placeholder resolution (e.g. #{Detail.Value:Detail.ValueEnd})
• Worksheet options (freeze panes, grouping, auto filter)
• OpenXML rendering with diagnostics and generation audit metadata

Architecture

flowchart LR
    A[DSL XML] --> B[DslParser]
    B --> C[Workbook AST]

    C --> D[LayoutEngine]
    E[ExpressionEngine] --> D
    F[StyleResolver] --> D

    D --> G[LayoutPlan]
    G --> H[WorksheetStateBuilder]
    H --> I[WorksheetState]
    I --> J[XlsxRenderer]
    J --> K[.xlsx Stream]

    R[ReportGenerator] -. orchestrates .-> B
    R -. orchestrates .-> D
    R -. orchestrates .-> H
    R -. orchestrates .-> J

Loading

Core modules:

• DSL/DslParser: parsing + optional XSD validation + issue collection
• ExpressionEngine: expression parsing/evaluation with cache support
• Styles/StyleResolver: style indexing and precedence composition
• LayoutEngine: layout expansion, repeat/use expansion, conditional rendering
• WorksheetState/WorksheetStateBuilder: merge/bounds validation and formula placeholder resolution
• Renderer/XlsxRenderer: OpenXML output generation
• ReportGenerator: end-to-end orchestration and phase logging

Installation

Prerequisites

• .NET SDK 8.0+

Add as a project reference (from source)

dotnet add <your-app>.csproj reference ExcelReport/ExcelReportLib/ExcelReportLib.csproj

Build

dotnet build ExcelReport.sln

Quick Start

1) Define DSL

<workbook xmlns="urn:excelreport:v1">
  <styles>
    <style name="HeaderCell" scope="cell">
      <font bold="true"/>
      <fill color="#F2F2F2"/>
      <border mode="cell" bottom="thin" color="#000000"/>
    </style>
  </styles>

  <sheet name="Summary">
    <cell r="1" c="1" value="@(root.Title)" />

    <grid rows="1" cols="2">
      <cell r="1" c="1" value="Item" />
      <cell r="1" c="2" value="Value" />
    </grid>

    <repeat r="3" c="1" direction="down" from="@(root.Items)" var="it">
      <grid rows="1" cols="2">
        <cell r="1" c="1" value="@(it.Name)" />
        <cell r="1" c="2" value="@(it.Value)" />
      </grid>
    </repeat>
  </sheet>
</workbook>

2) Generate workbook

using ExcelReportLib;

var dsl = File.ReadAllText("report.xml");
var data = new
{
    Title = "Sales Report",
    Items = new[]
    {
        new { Name = "A", Value = 100 },
        new { Name = "B", Value = 200 }
    }
};

var generator = new ReportGenerator();
var result = generator.Generate(dsl, data);

if (result.Succeeded)
{
    File.WriteAllBytes("report.xlsx", result.Output.ToArray());
}
else
{
    foreach (var issue in result.Issues)
    {
        Console.WriteLine($"[{issue.Severity}] {issue.Kind}: {issue.Message}");
    }
}

API Reference Summary

Primary API

• ReportGenerator
  • Generate(string dsl, object? data, ReportGeneratorOptions? options = null, CancellationToken cancellationToken = default)
  • GenerateFromFile(string dslFilePath, object? data, ReportGeneratorOptions? options = null, CancellationToken cancellationToken = default)
• ReportGeneratorOptions
  • EnableSchemaValidation
  • TreatExpressionSyntaxErrorAsFatal
  • Logger
  • RenderOptions
• ReportGeneratorResult
  • Output, Issues, LogEntries, Succeeded, AbortedByFatal, UnhandledException

Advanced/Composable APIs

• Parsing: DslParser, DslParserOptions, DslParseResult, Issue
• Expression: IExpressionEngine, ExpressionEngine, ExpressionContext, ExpressionResult
• Layout: ILayoutEngine, LayoutEngine, LayoutPlan, LayoutSheet, LayoutCell
• Styles: IStyleResolver, StyleResolver, StylePlan, ResolvedStyle
• Worksheet state: IWorksheetStateBuilder, WorksheetStateBuilder, WorksheetState, CellState
• Rendering: IRenderer, XlsxRenderer, RenderOptions, RenderResult
• Logging: IReportLogger, ReportLogger, LogEntry, LogLevel, ReportPhase

Project Structure

.
├── ExcelReport.sln
├── ExcelReport/
│   ├── ExcelReportLib/
│   │   ├── DSL/
│   │   ├── ExpressionEngine/
│   │   ├── LayoutEngine/
│   │   ├── Styles/
│   │   ├── WorksheetState/
│   │   ├── Renderer/
│   │   └── ReportGenerator.cs
│   └── ExcelReportLib.Tests/
│       ├── DslParserTests.cs
│       ├── LayoutEngineTests.cs
│       ├── RendererTests.cs
│       ├── ReportGeneratorTests.cs
│       └── ...
└── reports/

Testing

Run all tests:

dotnet test ExcelReport.sln

Run only library tests:

dotnet test ExcelReport/ExcelReportLib.Tests/ExcelReportLib.Tests.csproj

Run with coverage collector:

dotnet test ExcelReport/ExcelReportLib.Tests/ExcelReportLib.Tests.csproj --collect:"XPlat Code Coverage"

License

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Example:

• This project is licensed under the terms described in LICENSE.