From 0b5ae30f19d71ca6cc7b5867f3c988c570ecd579 Mon Sep 17 00:00:00 2001
From: myaaaaaaaaa <103326468+myaaaaaaaaa@users.noreply.github.com>
Date: Tue, 20 Aug 2024 08:02:24 -0400
Subject: [PATCH] Implement add/1 (#3144)

---
 docs/content/manual/dev/manual.yml |  8 +++++++-
 jq.1.prebuilt                      | 11 +++++++++--
 src/builtin.jq                     |  3 ++-
 tests/jq.test                      | 13 +++++++++++++
 tests/man.test                     |  4 ++++
 5 files changed, 35 insertions(+), 4 deletions(-)

diff --git a/docs/content/manual/dev/manual.yml b/docs/content/manual/dev/manual.yml
index 1eb7d9b8..2ec138fc 100644
--- a/docs/content/manual/dev/manual.yml
+++ b/docs/content/manual/dev/manual.yml
@@ -1300,7 +1300,7 @@ sections:
             input: '[1,[[],{"a":2}]]'
             output: ['[[0],[1,1,"a"]]']
 
-      - title: "`add`"
+      - title: "`add`, `add(generator)`"
         body: |
 
           The filter `add` takes as input an array, and produces as
@@ -1311,6 +1311,9 @@ sections:
 
           If the input is an empty array, `add` returns `null`.
 
+          `add(generator)` operates on the given generator rather than
+          the input.
+
         examples:
           - program: add
             input: '["a","b","c"]'
@@ -1321,6 +1324,9 @@ sections:
           - program: add
             input: '[]'
             output: ["null"]
+          - program: add(.[].a)
+            input: '[{"a":3}, {"a":5}, {"b":6}]'
+            output: ['8']
 
       - title: "`any`, `any(condition)`, `any(generator; condition)`"
         body: |
diff --git a/jq.1.prebuilt b/jq.1.prebuilt
index 7239e87d..151868fd 100644
--- a/jq.1.prebuilt
+++ b/jq.1.prebuilt
@@ -1,5 +1,5 @@
 .
-.TH "JQ" "1" "May 2024" "" ""
+.TH "JQ" "1" "July 2024" "" ""
 .
 .SH "NAME"
 \fBjq\fR \- Command\-line JSON processor
@@ -1340,12 +1340,15 @@ jq \'[paths(type == "number")]\'
 .
 .IP "" 0
 .
-.SS "add"
+.SS "add, add(generator)"
 The filter \fBadd\fR takes as input an array, and produces as output the elements of the array added together\. This might mean summed, concatenated or merged depending on the types of the elements of the input array \- the rules are the same as those for the \fB+\fR operator (described above)\.
 .
 .P
 If the input is an empty array, \fBadd\fR returns \fBnull\fR\.
 .
+.P
+\fBadd(generator)\fR operates on the given generator rather than the input\.
+.
 .IP "" 4
 .
 .nf
@@ -1361,6 +1364,10 @@ jq \'add\'
 jq \'add\'
    []
 => null
+
+jq \'add(\.[]\.a)\'
+   [{"a":3}, {"a":5}, {"b":6}]
+=> 8
 .
 .fi
 .
diff --git a/src/builtin.jq b/src/builtin.jq
index 802595ba..aa33cd4b 100644
--- a/src/builtin.jq
+++ b/src/builtin.jq
@@ -8,7 +8,8 @@ def unique: group_by(.) | map(.[0]);
 def unique_by(f): group_by(f) | map(.[0]);
 def max_by(f): _max_by_impl(map([f]));
 def min_by(f): _min_by_impl(map([f]));
-def add: reduce .[] as $x (null; . + $x);
+def add(f): reduce f as $x (null; . + $x);
+def add: add(.[]);
 def del(f): delpaths([path(f)]);
 def abs: if . < 0 then - . else . end;
 def _assign(paths; $value): reduce path(paths) as $p (.; setpath($p; $value));
diff --git a/tests/jq.test b/tests/jq.test
index 1502fbe0..d249bc19 100644
--- a/tests/jq.test
+++ b/tests/jq.test
@@ -642,6 +642,19 @@ map_values(.+1)
 [0,1,2]
 [1,2,3]
 
+[add(null), add(range(range(10))), add(empty), add(10,range(10))]
+null
+[null,120,null,55]
+
+# Real-world use case for add(empty)
+.sum = add(.arr[])
+{"arr":[]}
+{"arr":[],"sum":null}
+
+add({(.[]):1}) | keys
+["a","a","b","a","d","b","d","a","d"]
+["a","b","d"]
+
 #
 # User-defined functions
 # Oh god.
diff --git a/tests/man.test b/tests/man.test
index 7a9cf679..6c5eba39 100644
--- a/tests/man.test
+++ b/tests/man.test
@@ -358,6 +358,10 @@ add
 []
 null
 
+add(.[].a)
+[{"a":3}, {"a":5}, {"b":6}]
+8
+
 any
 [true, false]
 true