From edfbb300a32cb7c2314e7a58718457cef8231a7e Mon Sep 17 00:00:00 2001
From: Joachim Van Herwegen <joachimvh@gmail.com>
Date: Mon, 30 Oct 2023 08:39:59 +0100
Subject: [PATCH] Correctly convert FROM/CONSTRUCT algebra

---
 lib/sparql.ts                                 |  6 +-
 .../sparql-1.1/construct/construct-from.json  | 65 +++++++++++++++++++
 .../sparql-1.1/construct/construct-from.json  | 65 +++++++++++++++++++
 .../construct/construct-from.sparql           |  4 ++
 4 files changed, 139 insertions(+), 1 deletion(-)
 create mode 100644 test/algebra-blank-to-var/sparql-1.1/construct/construct-from.json
 create mode 100644 test/algebra/sparql-1.1/construct/construct-from.json
 create mode 100644 test/sparql/sparql-1.1/construct/construct-from.sparql

diff --git a/lib/sparql.ts b/lib/sparql.ts
index 12a4b7c..ccc1567 100644
--- a/lib/sparql.ts
+++ b/lib/sparql.ts
@@ -279,8 +279,12 @@ function translateExtend(op: Algebra.Extend): any
 function translateFrom(op: Algebra.From): GroupPattern
 {
     const result = translateOperation(op.input);
+    // Can't type as CONSTRUCT queries do not have `from` field in their type
+    let obj = result;
     // project is nested in group object
-    const obj: SelectQuery = result.patterns[0];
+    if (result.type === 'group') {
+        obj = result.patterns[0];
+    }
     obj.from = {
         default: op.default,
         named: op.named
diff --git a/test/algebra-blank-to-var/sparql-1.1/construct/construct-from.json b/test/algebra-blank-to-var/sparql-1.1/construct/construct-from.json
new file mode 100644
index 0000000..63bdb8d
--- /dev/null
+++ b/test/algebra-blank-to-var/sparql-1.1/construct/construct-from.json
@@ -0,0 +1,65 @@
+{
+    "default": [
+        {
+            "termType": "NamedNode",
+            "value": "http://example.com/data"
+        }
+    ],
+    "input": {
+        "input": {
+            "input": {
+                "patterns": [
+                    {
+                        "graph": {
+                            "termType": "DefaultGraph",
+                            "value": ""
+                        },
+                        "object": {
+                            "termType": "Variable",
+                            "value": "o"
+                        },
+                        "predicate": {
+                            "termType": "Variable",
+                            "value": "p"
+                        },
+                        "subject": {
+                            "termType": "Variable",
+                            "value": "s"
+                        },
+                        "termType": "Quad",
+                        "type": "pattern"
+                    }
+                ],
+                "type": "bgp"
+            },
+            "template": [
+                {
+                    "graph": {
+                        "termType": "DefaultGraph",
+                        "value": ""
+                    },
+                    "object": {
+                        "termType": "Variable",
+                        "value": "o"
+                    },
+                    "predicate": {
+                        "termType": "Variable",
+                        "value": "p"
+                    },
+                    "subject": {
+                        "termType": "Variable",
+                        "value": "s"
+                    },
+                    "termType": "Quad",
+                    "type": "pattern"
+                }
+            ],
+            "type": "construct"
+        },
+        "length": 100,
+        "start": 0,
+        "type": "slice"
+    },
+    "named": [],
+    "type": "from"
+}
diff --git a/test/algebra/sparql-1.1/construct/construct-from.json b/test/algebra/sparql-1.1/construct/construct-from.json
new file mode 100644
index 0000000..63bdb8d
--- /dev/null
+++ b/test/algebra/sparql-1.1/construct/construct-from.json
@@ -0,0 +1,65 @@
+{
+    "default": [
+        {
+            "termType": "NamedNode",
+            "value": "http://example.com/data"
+        }
+    ],
+    "input": {
+        "input": {
+            "input": {
+                "patterns": [
+                    {
+                        "graph": {
+                            "termType": "DefaultGraph",
+                            "value": ""
+                        },
+                        "object": {
+                            "termType": "Variable",
+                            "value": "o"
+                        },
+                        "predicate": {
+                            "termType": "Variable",
+                            "value": "p"
+                        },
+                        "subject": {
+                            "termType": "Variable",
+                            "value": "s"
+                        },
+                        "termType": "Quad",
+                        "type": "pattern"
+                    }
+                ],
+                "type": "bgp"
+            },
+            "template": [
+                {
+                    "graph": {
+                        "termType": "DefaultGraph",
+                        "value": ""
+                    },
+                    "object": {
+                        "termType": "Variable",
+                        "value": "o"
+                    },
+                    "predicate": {
+                        "termType": "Variable",
+                        "value": "p"
+                    },
+                    "subject": {
+                        "termType": "Variable",
+                        "value": "s"
+                    },
+                    "termType": "Quad",
+                    "type": "pattern"
+                }
+            ],
+            "type": "construct"
+        },
+        "length": 100,
+        "start": 0,
+        "type": "slice"
+    },
+    "named": [],
+    "type": "from"
+}
diff --git a/test/sparql/sparql-1.1/construct/construct-from.sparql b/test/sparql/sparql-1.1/construct/construct-from.sparql
new file mode 100644
index 0000000..c3ab93f
--- /dev/null
+++ b/test/sparql/sparql-1.1/construct/construct-from.sparql
@@ -0,0 +1,4 @@
+CONSTRUCT { ?s ?p ?o. }
+FROM <http://example.com/data>
+WHERE { ?s ?p ?o. }
+LIMIT 100