Add support to read from stdin

CHANGELOG.md

@@ -10,6 +10,7 @@ New features and improvements:
   * Relative coordinates are now used by default to reduce file size. If absolute coordinates are needed, they a new `--absolute` option for the `write` command.
   * A homing command (as defined by the `final_pu_params` configuration parameter) is no longer emitted between layers.
 * The viewer (`show` command) now catches interruptions from the terminal (ctrl-C) and closes itself (#321)
+* The `read` command now accepts `-` as file path to read from the standard input (#322)
 
 Bug fixes:
 * ...

tests/test_files.py

@@ -7,7 +7,7 @@
 import pytest
 
 import vpype as vp
-from vpype_cli import cli
+from vpype_cli import DebugData, cli
 
 from .utils import TEST_FILE_DIRECTORY
 
@@ -150,3 +150,18 @@ def test_read_with_viewbox(tmp_path):
     assert height == 100
     assert len(lc) == 1
     assert np.all(np.isclose(lc[0], np.array([0, 100 + 100j])))
+
+
+def test_read_stdin(runner):
+    svg = f"""<?xml version="1.0"?>
+    <svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"
+        width="1000" height="1000">
+      <circle cx="500" cy="500" r="40"/>      
+    </svg>
+    """
+
+    result = runner.invoke(cli, "read - dbsample dbdump", input=svg)
+    data = DebugData.load(result.output)
+
+    assert result.exit_code == 0
+    assert data[0].count == 1

vpype/io.py

@@ -200,7 +200,7 @@ def _extract_paths(group: svgelements.Group, recursive) -> _PathListType:
 
 
 def read_svg(
-    filename: str,
+    file: Union[str, TextIO],
     quantization: float,
     crop: bool = True,
     simplify: bool = False,
@@ -215,7 +215,7 @@ def read_svg(
     as tolerance.
 
     Args:
-        filename: path of the SVG file
+        file: path of the SVG file or stream object
         quantization: maximum size of segment used to approximate curved geometries
         crop: crop the geometries to the SVG boundaries
         simplify: run Shapely's simplify on loaded geometry
@@ -231,7 +231,7 @@ def read_svg(
     """
 
     # default width is for SVG with % width/height
-    svg = svgelements.SVG.parse(filename, width=default_width, height=default_height)
+    svg = svgelements.SVG.parse(file, width=default_width, height=default_height)
     paths = _extract_paths(svg, recursive=True)
     lc = _convert_flattened_paths(paths, quantization, simplify, parallel)
 
@@ -242,7 +242,7 @@ def read_svg(
 
 
 def read_multilayer_svg(
-    filename: str,
+    file: Union[str, TextIO],
     quantization: float,
     crop: bool = True,
     simplify: bool = False,
@@ -266,7 +266,7 @@ def read_multilayer_svg(
     as tolerance.
 
     Args:
-        filename: path of the SVG file
+        file: path of the SVG file or stream object
         quantization: maximum size of segment used to approximate curved geometries
         crop: crop the geometries to the SVG boundaries
         simplify: run Shapely's simplify on loaded geometry
@@ -281,7 +281,7 @@ def read_multilayer_svg(
          SVG dimensions
     """
 
-    svg = svgelements.SVG.parse(filename, width=default_width, height=default_height)
+    svg = svgelements.SVG.parse(file, width=default_width, height=default_height)
 
     document = Document()
 

vpype_cli/read.py

@@ -1,13 +1,13 @@
 import logging
-from typing import Optional, Tuple, cast
+import sys
+from typing import Optional, Tuple
 
 import click
 
 from vpype import (
     Document,
     LayerType,
     LengthType,
-    LineCollection,
     PageSizeType,
     global_processor,
     read_multilayer_svg,
@@ -21,7 +21,7 @@
 
 
 @cli.command(group="Input")
-@click.argument("file", type=click.Path(exists=True, dir_okay=False))
+@click.argument("file", type=click.Path(exists=True, dir_okay=False, allow_dash=True))
 @click.option("-m", "--single-layer", is_flag=True, help="Single layer mode.")
 @click.option(
     "-l",
@@ -89,6 +89,8 @@ def read(
 ) -> Document:
     """Extract geometries from a SVG file.
 
+    FILE may be a file path path or a dash (-) to read from the standard input instead.
+
     By default, the `read` command attempts to preserve the layer structure of the SVG. In this
     context, top-level groups (<svg:g>) are each considered a layer. If any, all non-group,
     top-level SVG elements are imported into layer 1.
@@ -162,6 +164,9 @@ def read(
     if display_landscape:
         width, height = height, width
 
+    if file == "-":
+        file = sys.stdin
+
     if single_layer:
         lc, width, height = read_svg(
             file,