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[compatibility] Backward compatibility with references to secrets and…
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… globals using the Mustache syntax (#515)
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@eolivelli
eolivelli authored Oct 2, 2023
1 parent 6dab9db commit 4bdeaa6
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41 changes: 36 additions & 5 deletions langstream-core/src/main/java/ai/langstream/impl/common/ApplicationPlaceholderResolver.java
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Original file line number Diff line number Diff line change
Expand Up @@ -36,6 +36,7 @@
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.stream.Collectors;
import lombok.SneakyThrows;
import lombok.extern.slf4j.Slf4j;
Expand Down Expand Up @@ -272,20 +273,50 @@ static Object resolveSingleValue(Map<String, Object> context, String template) {
return resolvePlaceholdersInString(template, context);
}

private static Set<String> ONLY_SECRETS_AND_GLOBALS = Set.of("secrets", "globals");

static String resolvePlaceholdersInString(String template, Map<String, Object> context) {
if (!template.contains("${") && template.contains("{{") && template.contains("}}")) {
// 0.x syntax
if (template.contains("{{{")) {
return resolvePlaceholdersInString(
template, context, "{{{", "}}}", ONLY_SECRETS_AND_GLOBALS);
} else {
return resolvePlaceholdersInString(
template, context, "{{", "}}", ONLY_SECRETS_AND_GLOBALS);
}
}
return resolvePlaceholdersInString(template, context, "${", "}", null);
}

private static String resolvePlaceholdersInString(
String template,
Map<String, Object> context,
String prefix,
String suffix,
Set<String> allowedRoots) {
StringBuilder result = new StringBuilder();
int position = 0;
int pos = template.indexOf("${", position);
int pos = template.indexOf(prefix, position);
if (pos < 0) {
return template;
}
while (pos >= 0) {
result.append(template, position, pos);
int end = template.indexOf("}", pos);
int end = template.indexOf(suffix, pos);
if (end < 0) {
throw new IllegalArgumentException("Invalid placeholder: " + template);
}
String placeholder = template.substring(pos + 2, end).trim();
String placeholder = template.substring(pos + prefix.length(), end).trim();

if (allowedRoots != null && allowedRoots.stream().noneMatch(placeholder::startsWith)) {
// this is a raw value like "The question is {{{value.question}}}"
// in a mustache template
// at this step of the preprocessor we allow mustache like syntax only for secrets
// and globals
// in order to keep compatibility with 0.x applications
return template;
}
Object value = resolveReference(placeholder, context);
if (value == null) {
// to not write "null" inside the string
Expand All @@ -301,8 +332,8 @@ static String resolvePlaceholdersInString(String template, Map<String, Object> c
}
}
result.append(value);
position = end + 1;
pos = template.indexOf("${", position);
position = end + suffix.length();
pos = template.indexOf(prefix, position);
}
result.append(template, position, template.length());
return result.toString();
Expand Down
130 changes: 130 additions & 0 deletions ...ream-core/src/test/java/ai/langstream/impl/common/ApplicationPlaceholderResolverTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -424,4 +424,134 @@ void testResolve() {
ApplicationPlaceholderResolver.resolveSingleValue(
context, "${ globals.foo.number }-${ globals.foo.map }"));
}

@Test
void testResolveCompatibilityTripleBraces() {
Map<String, Object> context =
Map.of(
"globals",
Map.of(
"foo",
Map.of(
"bar",
"xxx",
"number",
123,
"list",
List.of(1, 2),
"map",
Map.of("one", 1, "two", 2))));
assertEquals(
"xxx",
ApplicationPlaceholderResolver.resolveSingleValue(
context, "{{{globals.foo.bar}}}"));
assertEquals(
"123", // this is a string !
ApplicationPlaceholderResolver.resolveSingleValue(
context, "{{{globals.foo.number}}}"));
assertEquals(
"[1,2]", // this is a string !
ApplicationPlaceholderResolver.resolveSingleValue(
context, "{{{globals.foo.list}}}"));

// some spaces
assertEquals(
"123", // this is a string !
ApplicationPlaceholderResolver.resolveSingleValue(
context, "{{{ globals.foo.number }}}"));

// simple concat
assertEquals(
"123-xxx",
ApplicationPlaceholderResolver.resolveSingleValue(
context, "{{{ globals.foo.number }}}-{{{ globals.foo.bar }}}"));

// using a list, but in a string context
assertEquals(
"123-[1,2]",
ApplicationPlaceholderResolver.resolveSingleValue(
context, "{{{ globals.foo.number }}}-{{{ globals.foo.list }}}"));

// using a map, but in a string context
assertEquals(
"123-{\"one\":1,\"two\":2}",
ApplicationPlaceholderResolver.resolveSingleValue(
context, "{{{ globals.foo.number }}}-{{{ globals.foo.map }}}"));
}

@Test
void testResolveCompatibilityDoubleBraces() {
Map<String, Object> context =
Map.of(
"globals",
Map.of(
"foo",
Map.of(
"bar",
"xxx",
"number",
123,
"list",
List.of(1, 2),
"map",
Map.of("one", 1, "two", 2))));
assertEquals(
"xxx",
ApplicationPlaceholderResolver.resolveSingleValue(context, "{{globals.foo.bar}}"));
assertEquals(
"123", // this is a string !
ApplicationPlaceholderResolver.resolveSingleValue(
context, "{{globals.foo.number}}"));
assertEquals(
"[1,2]", // this is a string !
ApplicationPlaceholderResolver.resolveSingleValue(context, "{{globals.foo.list}}"));

// some spaces
assertEquals(
"123", // this is a string !
ApplicationPlaceholderResolver.resolveSingleValue(
context, "{{ globals.foo.number }}"));

// simple concat
assertEquals(
"123-xxx",
ApplicationPlaceholderResolver.resolveSingleValue(
context, "{{ globals.foo.number }}-{{ globals.foo.bar }}"));

// using a list, but in a string context
assertEquals(
"123-[1,2]",
ApplicationPlaceholderResolver.resolveSingleValue(
context, "{{ globals.foo.number }}-{{ globals.foo.list }}"));

// using a map, but in a string context
assertEquals(
"123-{\"one\":1,\"two\":2}",
ApplicationPlaceholderResolver.resolveSingleValue(
context, "{{ globals.foo.number }}-{{ globals.foo.map }}"));
}

@Test
void testDontBreakAMustacheValue() {
Map<String, Object> context =
Map.of(
"something",
Map.of("foo", Map.of("bar", "xxx", "number", 123, "list", List.of(1, 2))),
"globals",
Map.of(
"foo",
Map.of(
"bar",
"xxx",
"number",
123,
"list",
List.of(1, 2),
"map",
Map.of("one", 1, "two", 2))));
assertEquals(
"{{something.foo.bar}}",
ApplicationPlaceholderResolver.resolveSingleValue(
context, "{{something.foo.bar}}"));
}
}

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