Make it possible to have multiline statements in config

docs/ert/reference/configuration/index.rst

@@ -19,6 +19,7 @@ This chapter sets out everything you need to know to configure ERT.
 .. toctree::
    :maxdepth: 2
 
+   syntax
    data_types
    forward_model
    observations

docs/ert/reference/configuration/syntax.rst

@@ -0,0 +1,31 @@
+The ert configuration file format
+=================================
+
+The ert config file, workflows, workflow job configuration files and forward
+model configuration files all share the same syntax. These are lines starting
+with one keyword followed by arguments separated by whitespace. e.g.
+
+::
+
+        QUEUE_SYSTEM LOCAL
+        NUM_REALIZATIONS 12
+        -- A comment
+        FORWARD_MODEL DELETE_FILE(<FILES>="file1 file-- file3")
+
+        FORWARD_MODEL TEMPLATE_RENDER( \
+            <INPUT_FILES>=parameters.json, \
+            <TEMPLATE_FILE>=<CONFIG_PATH>/resources/SPE1.DATA.jinja2, \
+            <OUTPUT_FILE>=SPE1.DATA \
+        )
+
+So for example :code:`QUEUE_SYSTEM` is a keyword and :code:`LOCAL` is an
+argument. A comment is started with :code:`--`. :code:`FORWARD_MODEL` is a
+special keyword that starts an installed forward model step (e.g.
+:code:`DELETE_FILE`) with named forward model arguments inside parenthesis,
+(e.g. :code:`<FILES>` is set to :code:`file1 file-- file3`. Note that arguments
+can be surrounded by quotes (:code:`"`) to make spaces and :code:`--` part of
+the argument.
+
+As can be seen, you can have multi-line statements by escaping the newline with
+:code:`\\` (like with bash). NB: the newline has to follow directly after
+:code:`\\` without any spaces, tabs or other trailing whitespace.

src/ert/config/parsing/lark_parser.py

@@ -15,13 +15,12 @@
 from .types import Defines, FileContextToken, Instruction, MaybeWithContext
 
 grammar = r"""
-WHITESPACE: (" "|"\t")+
-%ignore WHITESPACE
-
 %import common.CNAME
 %import common.SIGNED_NUMBER    -> NUMBER
 %import common.NEWLINE          -> NEWLINE
 
+WHITESPACE: (" "|"\t"|"\\"NEWLINE)+
+%ignore WHITESPACE
 
 _STRING_INNER: /.+?/
 _STRING_ESC_INNER: _STRING_INNER /(?<!\\)(\\\\)*?/

test-data/ert/flow_example/flow.ert

@@ -14,6 +14,10 @@ OBS_CONFIG obs.txt
 
 GEN_KW FIELD_PROPERTIES field_properties_priors
 
-FORWARD_MODEL TEMPLATE_RENDER(<INPUT_FILES>=parameters.json, <TEMPLATE_FILE>=<CONFIG_PATH>/resources/SPE1.DATA.jinja2, <OUTPUT_FILE>=SPE1.DATA)
+FORWARD_MODEL TEMPLATE_RENDER( \
+    <INPUT_FILES>=parameters.json, \
+    <TEMPLATE_FILE>=<CONFIG_PATH>/resources/SPE1.DATA.jinja2, \
+    <OUTPUT_FILE>=SPE1.DATA \
+)
 
 FORWARD_MODEL FLOW

test-data/ert/snake_oil/snake_oil.ert

@@ -30,8 +30,24 @@ FORWARD_MODEL SNAKE_OIL_NPV
 FORWARD_MODEL SNAKE_OIL_DIFF
 
 RUN_TEMPLATE templates/seed_template.txt seed.txt
-GEN_KW SNAKE_OIL_PARAM templates/snake_oil_template.txt snake_oil_params.txt parameters/snake_oil_parameters.txt
-
-GEN_DATA SNAKE_OIL_OPR_DIFF INPUT_FORMAT:ASCII RESULT_FILE:snake_oil_opr_diff_%d.txt REPORT_STEPS:199
-GEN_DATA SNAKE_OIL_WPR_DIFF INPUT_FORMAT:ASCII RESULT_FILE:snake_oil_wpr_diff_%d.txt REPORT_STEPS:199
-GEN_DATA SNAKE_OIL_GPR_DIFF INPUT_FORMAT:ASCII RESULT_FILE:snake_oil_gpr_diff_%d.txt REPORT_STEPS:199
+GEN_KW \
+    SNAKE_OIL_PARAM \
+    templates/snake_oil_template.txt \
+    snake_oil_params.txt \
+    parameters/snake_oil_parameters.txt
+
+GEN_DATA \
+    SNAKE_OIL_OPR_DIFF \
+    INPUT_FORMAT:ASCII \
+    RESULT_FILE:snake_oil_opr_diff_%d.txt \
+    REPORT_STEPS:199
+GEN_DATA \
+    SNAKE_OIL_WPR_DIFF \
+    INPUT_FORMAT:ASCII \
+    RESULT_FILE:snake_oil_wpr_diff_%d.txt \
+    REPORT_STEPS:199
+GEN_DATA \
+    SNAKE_OIL_GPR_DIFF \
+    INPUT_FORMAT:ASCII \
+    RESULT_FILE:snake_oil_gpr_diff_%d.txt \
+    REPORT_STEPS:199

tests/ert/unit_tests/config/parsing/test_lark_parser.py

@@ -68,6 +68,22 @@ def test_that_realisation_is_a_alias_of_realization():
     assert config["NUM_REALIZATIONS"] == 1
 
 
+@pytest.mark.usefixtures("use_tmpdir")
+def test_that_new_line_can_be_escaped():
+    with open("config.ert", mode="w", encoding="utf-8") as fh:
+        fh.write(
+            dedent(
+                """
+                NUM_REALIZATIONS \
+                        1
+                """
+            )
+        )
+
+    config = parse("config.ert", schema=init_user_config_schema())
+    assert config["NUM_REALIZATIONS"] == 1
+
+
 @pytest.mark.filterwarnings(
     "ignore:.*Using DEFINE with substitution strings that are not of the form '<KEY>'.*:ert.config.ConfigWarning"
 )
@@ -79,7 +95,13 @@ def test_that_redefines_are_applied_correctly_as_forward_model_args():
         NUM_REALIZATIONS  1
         DEFINE <A> 2
         DEFINE <B> 5
-        FORWARD_MODEL MAKE_SYMLINK(<U>=<A>, <F>=<B>, <E>=<O>, R=Hello, <R>=R)
+        FORWARD_MODEL MAKE_SYMLINK( \\
+                <U>=<A>, \\
+                <F>=<B>, \\
+                <E>=<O>, \\
+                R=Hello, \\
+                <R>=R \\
+        )
         DEFINE <B> 10
         DEFINE B <A>
         DEFINE D <A>