pmcp 2.4.0

High-quality Rust SDK for Model Context Protocol (MCP) with full TypeScript SDK compatibility
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145

//! DSL helpers for ergonomic workflow construction
//!
//! Provides convenient functions to reduce boilerplate when building workflows.

use super::{
    data_source::DataSource,
    newtypes::{ArgName, BindingName},
};
use serde_json::Value;

/// Create a data source from a prompt argument
///
/// # Example
/// ```
/// use pmcp::server::workflow::dsl::prompt_arg;
///
/// let source = prompt_arg("user_name");
/// ```
pub fn prompt_arg(name: impl Into<ArgName>) -> DataSource {
    DataSource::prompt_arg(name)
}

/// Create a data source from a step's entire output
///
/// The `step` parameter should be the **binding name** set via `.bind()`,
/// not the step name passed to `WorkflowStep::new()`.
///
/// # Example
/// ```
/// use pmcp::server::workflow::dsl::from_step;
///
/// // If you have: WorkflowStep::new("my_step", ...).bind("output")
/// // Reference it as:
/// let source = from_step("output");  // Use binding name, not "my_step"
/// ```
pub fn from_step(step: impl Into<BindingName>) -> DataSource {
    DataSource::from_step(step)
}

/// Create a data source from a step's output field
///
/// The `step` parameter should be the **binding name** set via `.bind()`,
/// not the step name passed to `WorkflowStep::new()`.
///
/// # Example
/// ```
/// use pmcp::server::workflow::dsl::field;
///
/// // If you have: WorkflowStep::new("my_step", ...).bind("output")
/// // Reference a field as:
/// let source = field("output", "result");  // Use binding name, not "my_step"
/// ```
pub fn field(step: impl Into<BindingName>, field: impl Into<String>) -> DataSource {
    DataSource::from_step_field(step, field)
}

/// Create a constant data source
///
/// # Example
/// ```
/// use pmcp::server::workflow::dsl::constant;
/// use serde_json::json;
///
/// let source = constant(json!("Hello"));
/// ```
pub fn constant(value: Value) -> DataSource {
    DataSource::constant(value)
}

#[cfg(test)]
mod tests {
    use super::*;
    use serde_json::json;

    #[test]
    fn test_prompt_arg_helper() {
        let source = prompt_arg("input");
        match source {
            DataSource::PromptArg(name) => {
                assert_eq!(name.as_str(), "input");
            },
            _ => panic!("Expected PromptArg"),
        }
    }

    #[test]
    fn test_from_step_helper() {
        let source = from_step("step1");
        match source {
            DataSource::StepOutput { step, field } => {
                assert_eq!(step.as_str(), "step1");
                assert!(field.is_none());
            },
            _ => panic!("Expected StepOutput"),
        }
    }

    #[test]
    fn test_field_helper() {
        let source = field("step1", "output");
        match source {
            DataSource::StepOutput { step, field: f } => {
                assert_eq!(step.as_str(), "step1");
                assert_eq!(f.as_deref(), Some("output"));
            },
            _ => panic!("Expected StepOutput"),
        }
    }

    #[test]
    fn test_constant_helper() {
        let source = constant(json!({"key": "value"}));
        match source {
            DataSource::Constant(v) => {
                assert_eq!(v, json!({"key": "value"}));
            },
            _ => panic!("Expected Constant"),
        }
    }

    #[test]
    fn test_constant_with_primitives() {
        let s1 = constant(json!(42));
        let s2 = constant(json!("hello"));
        let s3 = constant(json!(true));

        assert!(matches!(s1, DataSource::Constant(_)));
        assert!(matches!(s2, DataSource::Constant(_)));
        assert!(matches!(s3, DataSource::Constant(_)));
    }

    #[test]
    fn test_dsl_in_workflow_step() {
        use crate::server::workflow::{ToolHandle, WorkflowStep};

        let step = WorkflowStep::new("step1", ToolHandle::new("create"))
            .arg("topic", prompt_arg("topic"))
            .arg("style", constant(json!("formal")))
            .arg("previous", from_step("step0"))
            .arg("specific", field("step0", "title"))
            .bind("result");

        assert_eq!(step.arguments().len(), 4);
    }
}